Error message - COPY NOT ALLOWED

I used ADE 2.0 for a long time and downloaded from there to my Kobo reader. I recently purchased a new laptop and downloaded ADE latest version and wanted to start using this laptop and new version instead. I downloaded some books from the library as I normally do, and then tried to copy to my Kobo reader. I could not copy to my Kobo and received an error message CE_COPY_NOT_ALLOWED - No permission to copy the book.

I also didn't know whether I should authorize my computer. I tried, but I cannot because it tells me my email address already exists and is being used.

I am frustrated. Please help.