Ĉiu el ni ricevas po unu dosieron kaj po du taskojn por la projekto.

Ĉiu means each or each one, so it is grammatically singular. That is why the verb is also singular: ricevas.

• ĉiu el ni = each of us
• ĉiuj el ni = all of us

So this sentence is focusing on the members of the group one by one, not on the group as a whole.

Here el means out of or from among.

So ĉiu el ni literally means each out of us or more naturally each of us.

This is a very common Esperanto pattern:

• unu el ili = one of them
• kelkaj el la studentoj = some of the students
• ĉiu el ni = each of us

For this meaning, el is the normal preposition.

Po is a distributive word. It shows that something is given to each person separately, at a rate of so much per person.

So:

• po unu dosieron = one file each
• po du taskojn = two tasks each

English often translates po as each, apiece, or per person, depending on the sentence.

A useful way to understand this sentence is:

• each of us receives one file each
• and two tasks each

Because there are two separate distributed amounts:

• po unu dosieron
• po du taskojn

Repeating po makes it clear that both quantities are meant for each person.

Without repeating it, the sentence would be less clear. Esperanto usually repeats po when it applies to more than one quantity in a list.

They still have -n because they are the direct objects of ricevas.

The verb ricevi means to receive, and what is received takes the accusative:

• receive a file → dosieron
• receive tasks → taskojn

The word po does not remove the accusative ending. It only adds the idea of distribution.

So:

• ricevas dosieron → direct object
• ricevas po unu dosieron → still a direct object, just now distributed

Because unu takes a singular noun, while du takes a plural noun.

• unu dosieron = one file
• du taskojn = two tasks

Then the accusative is added:

• singular object: dosiero → dosieron
• plural object: taskoj → taskojn

So the endings reflect both number and object function.

It would be similar, but not quite as precise.

• Ĉiu el ni ... po ... clearly emphasizes distribution to each individual
• Ĉiuj el ni ricevas unu dosieron kaj du taskojn can often be understood the same way in context, but it does not mark the distributive idea as explicitly

Using po removes ambiguity and makes the each person gets this amount idea very clear.

So the original sentence is the better choice when you want to stress one file per person and two tasks per person.

Por la projekto means for the project.

It tells us the purpose or intended use of the file and tasks: they are connected with the project.

So the sense is that each person receives:

• one file
• two tasks
• and these are for the project

In Esperanto, putting por la projekto at the end is a very natural position.

Because the grammatical subject is ĉiu, not ni.

Even though the meaning involves many people, Esperanto treats ĉiu as singular:

• Ĉiu ricevas = Each receives
• not Ĉiu ricevas with a plural verb, because Esperanto verbs do not change for person or number anyway, but the idea is still grammatically singular

So the structure is like English Each of us receives..., where each is the controlling word.