Hi Cédric,
To Install the GDPR cookie system, you need to follow these steps:
1) Open the PageBuilder
2) Click on the "+" icon on the left side of the screen
3) Go to Elements > Scripts
4) Drag&Drop the cookie script on your page (in the footer if you want that repeated on all pages of your site)
You can also double click on the block of script if you want to customize the message/link/colors