I posted a thread with a similar issue.
As a Mac users for 15+ years, I've always upgraded to the most recent OS. However, as a developer I wasn't thrilled with some of the changes in Catalina, mainly how root access is handled esp as there are two Applications folders, one being System read only.
I've always disabled SIP and Gatekeeper for reasons I won't get into and am well aware of the risks but maintain those Mac's off net or on extremely secure networks. During development I researched how to enable read/write user access using terminal but wasn't thrilled with the extra steps as at the time it wasn't permanent. Yet Xcode now requires Catalina moving forward and I haven't upgraded that Mac Pro for development but may have to now.
I haven't used the latest version of Catalina and didn't intend to until the newest developer beta's came out so will do some research on whether Apple has further locked root access and negated the terminal commands I found to enable access. For those in the same position or may know, has Catalina changed more so that the latest releases are even more inaccessible? Meaning can users still override SIP, Gatekeeper, and the lockdown on root/system access? Thanks for any advice and help.
Maybe try the script in the terminal that should give you permission and also try this in the terminal sudo mount -uw / ; killall Finder
This is the exact command I used back when I was running Catalina. Is this still working on the latest versions? It worked perfectly as it pretty much ran like Mojave.