Because Afrikaans usually follows a normal subject + verb + rest of sentence pattern in a main clause.
Here the parts are:
So the structure is:
This is very similar to English:
In this sentence, amptelik comes after the verb is, so it is functioning as a predicate adjective.
Compare:
In this position, Afrikaans adjectives usually stay in a simple base form.
If an adjective comes before a noun, it may sometimes take an -e ending:
So:
In this sentence, amptelik most naturally means official in the sense of formally recognized, valid, or approved.
Depending on context, amptelik can suggest:
So Die dokument is nou amptelik usually means something like:
You usually would not say it that way in neutral standard Afrikaans.
The most natural order here is:
That places nou before amptelik, which sounds normal and clear.
Afrikaans word order can sometimes vary for emphasis, but for a learner, is nou amptelik is the safest and most natural pattern.
A simple approximate pronunciation for English speakers is:
dee doh-kuh-MENT is noo AHMPT-uh-lik
A few helpful points:
This is only an approximation, but it is enough to get started.
Yes, in some contexts Afrikaans uses amptelik where English might use either official or officially, depending on sentence structure.
For example:
In your sentence, though, amptelik is best understood as official after the verb is:
Yes. Is is the present tense of wees (to be).
So:
Even though it implies a change that has happened, the sentence itself states the current situation: