@Kevin_Z I am not on Catalina yet, however I would think if your printer can be connected via WIFI, you would not need the TP-Link Printer app. Might be a temporary solution for some.

Be sure your SSID is not hidden and be close to the router for the setup.

If the default userid and password does not work which for most TP-link routers is admin/admin (see the owners guide for you model), then the procedure is to set it to factory specs and re-enter all...

I have my Canon MG7720 connected wireless on my TP-link router (Archer C8) and can print from PCs connected both by wire and over WIFI both 2.4 and 5 GHz. I have a hard drive connected to my USB port...

Need more info so we may help you. Model and version number and what type of issue are you having?

If the default userid and password does not work, then the method is to reset the router to factory specs and re-enter all of your settings including a new userid and password.