Downloadable files with login

Site URL: https://www.sitis.be/fr/smili

Hello !

What would be the solution to make some files only downloadable with a password and login previously attributed to our professional visitors ? I need to create some private documentation (dwg files and pdf price sheets) for my company (B2B). 

It's about files linked to an image in almost all of my regular pages and display in summary blocks.

It is currently not possible to do this with the squarespace tools. Any chance with coding or any external "plugin" ?

Here is an page example (block under "TELECHARGER") : https://www.sitis.be/fr/smili 

On Version 7.0– Brine family (Moksha template).

Thanks in advance for your huge help !!!

Aurelie