What OS are you using?
Has the catalog ever loaded in Elements 2020? Have you used a prior version? If so, the catalog is being converted for use in the later version. This can take a long time, particularly if you have a large catalog. So, perhaps be more patient for the initial conversion to take place. Even leave the machine running overnight.
If that is not the problem, press shift when clicking on the Organizer icon. That will bring up the Manage Catalogs dialog. You can then repair and optimize an existing catalog, create a new catalog (for further trouble-shooting), or convert an existing older version catalog again.