Can't write to the ~/Documents folder?

I'm trying to create a new folder inside my Documents folder, in order to copy files from a template structure into it.
Once I request the folder name from the user, I use "Execute Shell Script" with input from Nothing, execute text script and display result in a window. The shell command is mkdir -p "$KMVAR_projectFilePath"

The log returns :
Execute a Shell Script failed with script error: mkdir: ~/Documents/projects/wrk/blablih8: Read-only file system

I've added Keyboard Maestro to the Full disk access list in Systems Preferences, on the off chance that this was the problem, but no.

Is there a special set of restrictions on KM maestro writing files to the ~/Document folder? Maybe it's because I'm running Big Sur?

Check this out, it may help:

Thanks, but no dice. The error is that the actual path is Read-Only

Execute a Shell Script failed with script error: mkdir: ~/Documents/projects/wrk/blihblih: Read-only file system