git error "[my repository] is on a file system that does not record ownership"

I'm getting this error between two W10 systems running a VPN and RDP. My local system "My" has an area c:\cap2office that is a Git repository.
The remote system "Remote" has My C: drive mapped to its drive S: I can see the C:\cap2office directory as S:\cap2office on the remote system.
And the username on the remote system is different from the username on my local system.

On Remote, I typed "git status" and it complained about mismatching ownership and suggested defining GIT_TEST_DEBUG_UNSAFE_DIRECTORIES=true, so I did that on the Remote system and that warning went away.

But it still says:

warning: '//tsclient/C/cap2office' is on a file system that does not record ownership
fatal: unsafe repository ('//tsclient/C/cap2office' is owned by someone else)
To add an exception for this directory, call:
        git config --global --add safe.directory '%(prefix)///tsclient/C/cap2office'

So on the Remote system, I did:

git config --global --add safe.directory S:/cap2office

On the Remote, I can do git config --list

And in addition to the error (3 times):

   warning: '//tsclient/C/cap2office' is on a file system that does not record ownership
I see this at the end, so the safe.directory did get added:
    safe.directory=S:/cap2office

But when I do 'git status', I still get:

warning: '//tsclient/C/cap2office' is on a file system that does not record ownership
fatal: unsafe repository ('//tsclient/C/cap2office' is owned by someone else)
To add an exception for this directory, call:
        git config --global --add safe.directory '%(prefix)///tsclient/C/cap2office'

So I also tried

git config --global --add safe.directory //tsclient/C/cap2office
warning: '//tsclient/C/cap2office' is on a file system that does not record ownership
warning: encountered old-style '//tsclient/C/cap2office' that should be '%(prefix)///tsclient/C/cap2office'
fatal: unsafe repository ('//tsclient/C/cap2office' is owned by someone else)
To add an exception for this directory, call:
        git config --global --add safe.directory '%(prefix)///tsclient/C/cap2office'

Any ideas? What should %prefix be, maybe the drive mapping doesn't work?

BTW, I'm curious where the .gitconfig file is located.
It doesn't appear to be C:\user\accountname\.gitconfig as advertised or under the program files Git area.

Solution

What should %prefix be, maybe the drive mapping doesn't work?

Actually, as I detailed here, you must use the actual string %(prefix)

The value of this setting is interpolated, i.e.

~/<path> expands to a path relative to the home directory and

%(prefix)/<path> expands to a path relative to Git's (runtime) prefix.

And:

I'm curious where the .gitconfig file is located.

Do a git config --show-scope --show-origin -l: you will see all the config files and their path.