Same problem here. Seems like this dialog-box interacting with Discogs, is running on a very old browser, that doesn't handle the scripts anymore. If you look at the source code (by right-clicking), it returns an empty page after you click "Authorize". If I paste the link from the previous authorization page in my browser, it generates a reply token. Just don't know where to put that. I looked at the windows registry entries, there's entries for Discogs and DiscogsSearch, but I don't really know how to insert this token there.
I know the program is now free, which means it will not be updated, which is fine feature-wise but this is broken functionality that needs to be patched somehow, so if anyone knows how to? Or if we can update this internal browser to a current version?