What version of Premiere Elements do you have and on what computer operating system is it running?
Are you using this AdobeID/Password for the first time or have you tried and downloaded the themes earlier?
You can check the logs from charles or Fiddler.
Launch Charles or fiddler(its free tool) and try to sign in.
Just getting back into action after some traveling and noticed that we have not heard from you with the details needed to help us help you.
First we need to know what version of Premiere Elements that you are using and on what computer operating system it is running on.
Second, we need to know how your Adobe ID and password are factoring into this.
Based on what you wrote, I am suspecting that you are trying to obtain photoshop.com plus only Content from earlier version of Premiere Elements. That photoshop.com is gone and the associated themes are no longer available via the process that you are trying to use. Interestingly, many of those photoshop.com plus themes are available in more current versions free as part of the program. But, all of what I just wrote is speculation, guessing.
Looking forward to more information from you on your issue.