How does the Box Service from the Russian Post work?

Question

API

Hi, someone figured out:
a) about the algorithm of the Box-Service service from the Russian Post.
As I was told at my post office. All registration (including weighing envelopes (I only have documents), printing envelopes together with printing track numbers on them, register formation - I MUST DO IT MYSELF + make an advance payment to the account of the Russian Post, for the Box Service itself.

I honestly thought, I give them the filled envelopes, and they write to me in my personal account what was sent where with the attached Track numbers
b) how to tie the whole thing with CRM there are cases?