Stretching and api upgrades

Good afternoon
https://www.figma.com/file/u0PkBZMqsi9hReOl908Vgf/Weave-E-Commerce-(Copy)?node-id=0:1
General concept:
We have api with n number of mailboxes https://api.mailslurp.com/swagger-ui/index.html
The user can buy one of the three packages, and entering the cabinet get his portion of boxes for management (layouts on the right)
After the purchase and authorization, the user can send, delete, and interact with the LC, everything is in the api.
The main problem is to divide a single API account into different users. Otherwise, everything seems to be standard.
Layout of layouts we will provide
Include your budget and prices in the response, thanks!