Help creating a formula

Hello guys,

I'm new here. Sorry for jump in straight away with my question

So here is my problem:

-I have two separated xlsx documents
In document 1 i have this:

Document 1.xlsx

And in document 2 i have this:

Document 2.xlsx

What I want is to create a ("global") formula that automatically fills document 2 table with the sum of the units of specific clients and codes. For example:

In document 2, it should appear in cell B3 the number 200 since for client A and with code 1 we have two values (E3 and E8, 20+100).
And so on: If B with code 1, sum the unit values in cell B4 (etc).

I hope i want too much confunsing, thanks for the help.

ANCF