As I had the same problem, I contacted Customer Car with above link.
The agent "Tshering" told me to go to the forum and ask for help here.
Windows 10 pro 64bit 1511 german
ADE 18.104.22.168278 german
error message "Error! Check activation"
What i have done:
1. reinstall ADE - no change, and it said: already authorized
2. tried to deactivate the authorization - failed with message: cannot be done in the moment, try later
3. contacted Customer support, - failed with message: contact forum, they will help you
This was the first think I did. However, your colleague advised to write in this chat.
Thank you. Lidia