What is the GP version installed on the client?. For macOS Catalina, GP version 5.0.4 and later are supported
Following link has the compatability matrix list for your reference
As Josh said, upgrade to latest version. There were changes to the extension used (Kernal versus System) in Catalina, and you'll want 5.1.3. (I believe) minimum, however, there are significnat fixes in 5.1.5 as well.
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