To load some files only for some specific user(s)

Here is a suggestion to automate some process with my final users.

Via the admin:
1 / Create the customer area (user account area)
2/ To put some documents on the user account.
3/ Extra:
To let the user to also upload some documents on his user account.

The main goal is :
I prepare some pdfs (quotes for some services) for my users.
Each get "his" pdf.
Each user can print out his pdf and modify the contents if needed.
Then, is possible, the user can load the "new version" of the pdf file.

Bonus:
I will add "stipe" or "paypal" to display the amount to be paid by the user, for the services I can provide them.
This "amount" will be displayed only on the user account.

Do you think one (or more) of your plugin can help me out ?

I don't need/want to use WooCommerce.

For the payment, I just need to put a "custom" paypal link in the user account.

I will manage the payment and the bill directly inside Paypal website.

Do you have an other plugin to recommend me ?