Die vorm en die dokument moet al twee vandag by die kantoor wees.

Because Afrikaans normally repeats the definite article when two definite nouns are joined with en.

So die vorm en die dokument means the form and the document.

Repeating die makes it clear that both nouns are definite and separate items. In this sentence, that is the most natural wording.

Yes, die is the usual definite article in Afrikaans, and it generally corresponds to English the.

A very important point for English speakers:

• Afrikaans does not have grammatical gender the way German or Dutch do.
• die does not change for masculine, feminine, or neuter nouns.
• It is also used with plural nouns.

So:

• die vorm = the form
• die dokument = the document
• die dokumente = the documents

Al twee means both.

It emphasizes that not just one of the two items, but both of them, must be at the office today.

Literally, it is something like all two, but in normal English you should just think of it as both.

Yes. These are very close in meaning.

Common alternatives are:

• al twee
• altwee
• albei

So these are all possible:

• Die vorm en die dokument moet al twee vandag by die kantoor wees.
• Die vorm en die dokument moet altwee vandag by die kantoor wees.
• Die vorm en die dokument moet albei vandag by die kantoor wees.

In many contexts, albei is especially common and natural.

Because Afrikaans often puts the main verb infinitive at the end when there is a modal verb such as moet.

Here:

• moet = must / have to
• wees = be

So the structure is:

subject + moet + other information + wees

This is very normal in Afrikaans:

• Ek moet gaan. = I must go.
• Ons moet werk. = We must work.
• Die vorm en die dokument moet ... wees. = The form and the document must ... be.

Because moet only shows necessity. It does not tell you what must happen.

You still need the main verb. In this sentence, the main idea is that the form and the document must be somewhere, so Afrikaans uses wees.

Compare:

• Ek moet werk. = I must work.
• Sy moet wag. = She must wait.
• Die vorm en die dokument moet by die kantoor wees. = The form and the document must be at the office.

Without wees, the sentence would feel incomplete.

By die kantoor usually means at the office.

This is different from:

• in die kantoor = in the office / physically inside the office room
• na die kantoor = to the office / movement toward the office

So by die kantoor wees means that the items must be at the office, or with the office, not necessarily emphasizing movement or being physically inside a particular room.

Because Afrikaans verbs do not change form much for person or number in the present tense.

So you use moet with:

• ek
• jy
• hy / sy
• ons
• hulle
• and also with a compound subject like die vorm en die dokument

Examples:

• Ek moet
• Ons moet
• Hulle moet
• Die vorm en die dokument moet

So there is no separate plural form here.

Yes. Afrikaans word order is flexible enough that vandag can move, depending on emphasis.

For example:

• Die vorm en die dokument moet al twee vandag by die kantoor wees.
• Die vorm en die dokument moet vandag al twee by die kantoor wees.
• Vandag moet die vorm en die dokument al twee by die kantoor wees.

These are all possible, but the focus shifts slightly:

• putting vandag earlier gives today more emphasis
• keeping it where it is sounds natural and balanced

Yes, it is natural Afrikaans.

A native speaker might also say:

• Die vorm en die dokument moet albei vandag by die kantoor wees.
• Die vorm en die dokument moet altwee vandag by die kantoor wees.

All of these are normal. The version with al twee is clear and grammatical, and it strongly highlights that both items are required.