Linke tıklamadan önce parolayı kontrol et.

Because the verb tıklamak normally takes the dative case in Turkish:

• bir şeye tıklamak = to click on something

So:

• link = link
• linke = to/on the link

English uses a direct object with click very often, but Turkish usually treats it more like click on something.

So Linke tıkla is the standard pattern, not Linki tıkla.

This is a very common Turkish pattern:

• verb + -madan/-meden + önce = before doing something

Here:

• tıkla- = click
• tıklamadan = without clicking
• tıklamadan önce = before clicking

So the whole chunk functions like before clicking the link.

You can learn it as a set pattern:

• gitmeden önce = before going
• konuşmadan önce = before speaking
• yatmadan önce = before going to bed

Good question. The ending -madan/-meden is historically built with the negative marker, and by itself it usually means without doing:

• tıklamadan = without clicking

But when Turkish adds önce, the whole expression -madan önce is used to mean before doing.

So in this sentence, you should understand tıklamadan önce as one common structure, not as a true negative idea in English.

Because Turkish often uses words like önce after the word or phrase they belong to.

So Turkish says:

• tıklamadan önce
  literally something like clicking-without before

Where English says:

• before clicking

This is normal Turkish structure.
A few similar examples:

• yemekten önce = before the meal / before eating
• çıkmadan önce = before leaving

Because parolayı is the definite direct object of the verb kontrol et.

In Turkish, a specific or definite direct object usually takes the accusative ending.

• parola = password
• parolayı = the password

The -y- is just a buffer consonant. Turkish adds it when a vowel-initial ending attaches to a word that already ends in a vowel:

• parola + -(y)ı → parolayı

So:

• parola kontrol et would sound incomplete or unnatural here
• parolayı kontrol et = check the password

It is a compound verb made from:

• kontrol = control / check
• etmek = to do, to make

Together, kontrol etmek means to check.

In Turkish, many verbs are built this way:

• yardım etmek = to help
• fark etmek = to notice
• kontrol etmek = to check

They are written as two words, but they function as a single verbal idea.

Et is the second-person singular imperative of etmek.

So the sentence is a command addressed to you:

• kontrol et = check

Turkish often leaves the subject unstated when it is obvious. Here the hidden subject is:

• sen = you

But Turkish normally does not say Sen ... kontrol et unless it wants extra emphasis.

If you wanted to be polite or speak to more than one person, you would say:

• kontrol edin

Yes, this word order is very normal.

Turkish often puts:

1. time or condition information first
2. object before the verb
3. verb at the end

So:

• Linke tıklamadan önce = before clicking the link
• parolayı = the password
• kontrol et = check

That gives the natural order:

• Linke tıklamadan önce parolayı kontrol et.

You can move things around for emphasis, though:

• Parolayı linke tıklamadan önce kontrol et.

That still works, but the original sentence is a very natural neutral order.

Yes. Because the command ends with et, it is directed at one person informally.

So this is the kind of form you would use with:

• a friend
• a child
• someone you speak casually to
• general instructions in some contexts

For a polite or plural version, Turkish would use:

• Linke tıklamadan önce parolayı kontrol edin.

So the difference is:

• kontrol et = check! (informal singular)
• kontrol edin = check! (polite or plural)