Problem with payment (user identification)

Hi, I’ve set up a course. Evering is set, lessons, etc. When I am on the course page section:
https://yannickpage.ca/lp-cours/

When I click on ”Acheter ce cours” wich mean in english: Buy this course, I then go to this page:
https://yannickpage.ca/lp-caisse/

The problem is that I cannot register as a new customer. Even if i’m not connected, it seem that it consider me as already a user.

I’ve tried on another computer and yet, still this …

Thanks for the support, I appreciated. Sorry for my english, hope you get it.

The page I need help with: [log in to see the link]