The permissions of the modules folders and files must be 755.

To perform this check, you must connect via FTP to your Prestashop.

To connect via FTP, you need access credentials to your server and an FTP program, such as:

FileZilla (Windows / macOS)
Cyberduck (Windows / macOS / Linux)
Transmit (macOS)

Once connected you will have to look for the module folder that you find inside the site root, inside the modules folder