Ok,
sorry for disturbance. I just logged in and now I have access to the pre-alpha forum (don't know why since I didn't do anything particular).
Thanks for your help
@NQ-Nyzaltar Yes, I just did and it doesn't change anything... :-/
EDIT: (and I am 100% sure I purchased a gold plege way before the 7th of september (also I can download the pre-alpha))