Ako ti nešto nedostaje u prijavi, reci mi odmah pa ćemo zajedno završiti sve.

Because nedostajati works differently from English to be missing.

In Croatian, nešto ti nedostaje literally means something like something is lacking to you or you are missing something.

So:

• nešto = the thing that is missing
• ti = to you (dative)
• nedostaje = is missing / is lacking

There is no need for si here, because this is not a form of biti (to be). The verb is nedostajati.

So:

• Ti nešto nedostaje = incorrect
• Nešto ti nedostaje = correct

Ti is the dative singular form of ti / tebi, meaning to you.

In this sentence:

• Ako ti nešto nedostaje = If you’re missing something / If something is missing for you

Croatian often uses the dative with verbs expressing that something is lacking, needed, pleasing, etc.

Compare:

• Nedostaje mi dokument. = I’m missing a document.
• Nedostaje ti potpis. = You’re missing a signature.

So ti does not mean the subject you in the English sense. It marks the person affected.

Nešto means something, and here it is in the nominative case because it is the grammatical subject of nedostaje.

Structure:

• nešto nedostaje = something is missing
• ti nešto nedostaje = something is missing to you

Even though in English we often say you are missing something, Croatian makes something the subject.

That is why nešto stays in its basic form here.

U prijavi means in the application/form, and prijavi is in the locative singular.

After u, Croatian uses:

• accusative for movement into something
• locative for location in something

Here there is no movement, just location:

• u prijavi = in the application
• u školi = at school / in school
• u dokumentu = in the document

The base noun is prijava. Its locative singular is prijavi.

Prijava is a common Croatian noun that can mean:

• application
• registration
• report
• sometimes submission

The exact meaning depends on context.

In this sentence, u prijavi most naturally means in the application or in the form/application submission.

So this sentence is probably about a form, application, or submission that may be incomplete.

Yes. Reci is the imperative singular of reći (to say / to tell).

So:

• reci mi = tell me
• reci odmah = say/tell it right away

This is a direct instruction to one person.

Compare:

• reci! = tell! (to one person)
• recite! = tell! (to more than one person / formal)

So reci mi odmah means tell me right away.

Because with reći meaning to tell someone, Croatian uses the dative for the person receiving the information.

So:

• reci mi = tell me
• reci mu = tell him
• reci nam = tell us

Not:

• reci mene = incorrect in this meaning

This is similar to English tell me, where me is the recipient, but in Croatian that recipient is in the dative.

Here pa means something like:

• and then
• so
• in that case
• then

In this sentence it links the two ideas naturally:

• reci mi odmah pa ćemo zajedno završiti sve
• tell me right away, and then / so we’ll finish everything together

It is very common in spoken and written Croatian to connect actions this way.

It is not exactly the same as plain i (and). Pa often suggests consequence or the next step.

Because the sentence is talking about a future action:

• pa ćemo zajedno završiti sve = then we will finish everything together

Croatian forms the future tense with:

• the short form of htjeti (ću, ćeš, će, ćemo, ćete, će)
• plus the infinitive

So:

• ćemo završiti = we will finish

If you said završimo, that would usually be present tense or part of another construction, not the normal future meaning here.

In Croatian future tense, the short auxiliary usually comes before the infinitive when there is another word before it or when it is not at the very beginning in a special position.

So:

• Završit ćemo sve.
• Pa ćemo završiti sve.

Both are normal.

In this sentence, after pa, the natural order is:

• pa ćemo zajedno završiti sve

This is a standard future-tense pattern.

Zajedno means together.

So:

• zajedno završiti sve = finish everything together

It tells you how the action will be done: cooperatively, with the speaker and the other person both involved.

It is an adverb.

Sve means everything.

In this sentence it refers broadly to all the remaining things that need to be completed in the application or process.

So:

• završiti sve = finish everything

Croatian often uses sve when the context already makes clear what everything refers to.

The word order is natural, but not completely fixed.

The given sentence:

• Ako ti nešto nedostaje u prijavi, reci mi odmah pa ćemo zajedno završiti sve.

is very idiomatic.

Some parts can move, but not all changes sound equally natural.

For example:

• Ako ti u prijavi nešto nedostaje, reci mi odmah... = also correct
• Reci mi odmah ako ti nešto nedostaje u prijavi... = also correct

But Croatian clitics like ti, mi, ćemo tend to follow special placement rules, so you cannot move them completely freely.

For example, ti and mi are short unstressed forms and usually appear near the beginning of their clause.

Yes, in many everyday contexts you could say:

• Ako ti nešto fali u prijavi...

This would also mean If something is missing in the application...

However:

• nedostaje is a bit more neutral or formal
• fali is more colloquial in many regions

Since prijava sounds somewhat administrative, nedostaje fits very well stylistically.

Odmah means immediately / right away.

So:

• reci mi odmah = tell me right away

It adds urgency, but in a helpful way. The speaker is saying: if anything is missing, let me know immediately so we can solve it together.

Without odmah, the sentence would still be correct, but it would sound less prompt:

• Reci mi pa ćemo zajedno završiti sve.

With odmah, the speaker emphasizes quick communication.