How can I get RT to show my desktop folders/files?
What version of RT?
Just downloaded the latest today, 5.8
I’m assuming for the moment that you are talking about the one that is shown here.
If this is so than you are using an old (February 4, 2020) version that should not be used any longer. This old version has bugs that are already fixed, lacks support for newer gear and does not have some of the new/upgraded functionality that is present in a more recent version.
Have a look here for an up-to-date version:
Tried both Mac installs, iMac won’t open either
Does RT have disk access in the Gatekeeper preference?
where/how do I check that?
Its in the macOS system preferences.
Under security/prefrences, files/folders, RT is the only app not in the list. I checked permissions and I have full read/write.