I cant authorize my computer

I bought a book, and instructed to install Adobe Digital Editions 4.5. When I open the program my book isn't there, so I tried adding a book but it doesn't see it as a acsm ext. So I double clicked on the downloaded book and the program comes up asking to authorize and after putting in E Book Vendor, i selected Adobe and then my ID but after pressing authorize it cam up with this error...

"

ACTIVATION SERVER ERROR

code:E_ADEPT_REQUEST_EXPIRED http://adeactivate.adobe/adept/Activate

2015-09-26T14:29:39-07:00%

20(1443302979000)%20before%20215-09-26T16:58:52-07:00%20(1443311932064

So I have contacted support on chat and was asked to erase authorization but in the help section but the letters are greyed out so nothing happens.

I am not a computer geek and this is annoying just to read my book. Any ideas on this.

Thanks

Rick