Can't download epub or remove the autorisation from computer

Hi there!

I'm using Digital edition since a few year now for downloading ebooks and epubs for work. It was working quite well, but since april 2018, it's impossible to download a book. It give's the message "Error! Check activation". I've been uninstalling and reinstall the program a few times and nothing happen. I've even download the 3.1 version instead of the 4.5.8 version as user suggest in a older message on this forum.

I can't remove the autorisation request from my computer. I'm on windows 10 home.

Is anyone have a solution?

Thanks for you help!