Înainte de a depune cererea, solicitantul autentifică copia legalizată.

Because înainte de is the normal Romanian structure for before, and when it is followed by a verb, Romanian usually uses:

înainte de a + infinitive

So:

• înainte de a depune = before submitting / before depositing / before filing

The little word de belongs to the expression înainte de, and a depune is the infinitive form of the verb.

This is a very common pattern in formal Romanian:

• înainte de a semna = before signing
• înainte de a pleca = before leaving
• înainte de a completa formularul = before filling out the form

Yes, a depune is the infinitive.

Romanian has two common ways to say before doing something:

• înainte de a depune cererea
• înainte să depună cererea

Both are possible, but they feel a little different:

• înainte de a + infinitive is often more formal and very common in administrative or written language.
• înainte să + subjunctive is also natural, and often feels a bit more verbal or conversational.

In your sentence, înainte de a depune cererea fits the official, bureaucratic style very well.

Those endings are the Romanian definite article. Unlike English, Romanian usually attaches the to the end of the noun.

So:

• solicitant = applicant

• solicitantul = the applicant

• cerere = request / application

• cererea = the request / the application

• copie = copy
• copia = the copy

This is one of the biggest differences from English. Instead of a separate word like the, Romanian often uses a suffix:

• masculine singular: often -ul
• feminine singular: often -a
• other patterns exist too

So the sentence is talking about specific things:

• the applicant
• the application
• the copy

Because legalizată agrees with copia, and copia is feminine singular.

Agreement in Romanian works a lot like in other Romance languages: adjectives change form to match the noun.

• copie = feminine singular
• copie legalizată = legalized/certified copy

Compare:

• document legalizat = legalized document
• copie legalizată = legalized copy
• documente legalizate = legalized documents
• copii legalizate = legalized copies

So legalizată is feminine singular because it describes copia.

In Romanian, when the adjective comes after the noun, the noun usually carries the definite article, and the adjective just agrees normally.

So:

• copie legalizată = a legalized copy
• copia legalizată = the legalized copy

The definiteness is already shown on copia. The adjective legalizată does not need an extra article in this position.

This is normal Romanian structure:

• cartea interesantă = the interesting book
• camera mare = the big room
• cererea completată = the completed application

Romanian often uses the present tense in formal instructions, procedures, and administrative descriptions.

So solicitantul autentifică can mean something like:

• the applicant authenticates
• the applicant is to authenticate
• the applicant must authenticate

The exact English translation depends on context, but the Romanian present tense is very normal here. Official language often describes required steps as plain facts:

• Solicitantul completează formularul.
• Atașează documentele necesare.
• Depune cererea la ghișeu.

This style can sound a bit like procedure manuals or legal instructions in English.

Autentifică is the 3rd person singular present indicative of a autentifica.

Conjugation:

• eu autentific = I authenticate
• tu autentifici = you authenticate
• el/ea autentifică = he/she authenticates

In your sentence, the subject is solicitantul (the applicant), which is singular, so autentifică is the correct form.

Yes, they are related, and that can be confusing.

Very roughly:

• a autentifica = to authenticate, certify as genuine, officially validate
• legalizat(ă) = legalized, certified, notarized

In administrative/legal Romanian, these words can be close in meaning, but they are not always exact synonyms in every context. Their precise meaning depends on the procedure and the institution involved.

So a learner should not expect a perfect one-to-one English match every time. In official Romanian, these terms often belong to a specific legal or bureaucratic system.

Because that whole phrase is an introductory time expression: Before submitting the application...

Romanian, like English, often separates this kind of introductory element with a comma.

So the structure is:

• Înainte de a depune cererea, = Before submitting the application,
• solicitantul autentifică copia legalizată. = the applicant authenticates the legalized copy.

You may also see the time phrase placed at the end:

• Solicitantul autentifică copia legalizată înainte de a depune cererea.

That version usually does not need a comma.

It is not completely fixed. Romanian word order is fairly flexible, although this sentence uses a very standard and natural order.

Current structure:

• Înainte de a depune cererea, solicitantul autentifică copia legalizată.

A very natural alternative is:

• Solicitantul autentifică copia legalizată înainte de a depune cererea.

Both mean essentially the same thing.

Inside the main clause, Romanian often prefers:

• subject + verb + object so:
• solicitantul autentifică copia legalizată

That is the clearest, most neutral order.

It can mean both, depending on context.

Cerere is a broad administrative word that may mean:

• request
• application
• petition

In bureaucratic or institutional contexts, cererea very often means the application.

So if the meaning shown to the learner is application, that is completely normal. But it is useful to know that cerere is not limited to only one English translation.