Error Message on Adobe Digital Editions check Activation

when I go to download an  ebook from my libray I get the message Error:check Activation.  when I do that, it says that my computer is activated.  I believe I may be having a problem because I tried downloading Adobe Digital Editions on a different computer, but did not activate it to complete the download.  Now I am home on my own computer and my Adobe Digital Editions is not working.  I am now receiving the Error message about checking Activation. 

I have found where I can deactivate my account and then reactivate it, I know how to deactivate, but do not know how to activate again.  I really do not want to lose what I have in Adobe Digital Editions right now.  Can you please advise me on how to activate again.  I am using Windows 10.

Ev