Let's rewind this ... so you already had a 3.8.3 under XAMPP (which installs the entire stack + moodle code [version 3.8.3] in a moodle directory.
Was the hidden .git directory already in the moodle code directory?
You then decided, rather than getting the entire XAMPP stack to attempt upgrading the moodle you had to the highest version via git.
You say that went well ... so you had to change into the existing moodle code directory, and issue at least 3 git commands.
git branch --track MOODLE_311_STABLE origin/MOODLE_311_STABLE
git checkout MOODLE_311_STABLE
and then, finally,
git pull
Then run the upgrade.php script in admin/cli/
From the moodle code directory, what does the command: git branch -a
show?
And what version of code do you have? Look at version.php file at code root for a 'release' line. What does that show/say?
Comment: the git repo for Moodle doesn't have a linux version and a windows version repo. If one goes to just downloads and looks, one will see a .zip for Windows. That's actually a larger download than the gzip for Linux. So using git on Windows in your case might not work at all!!!
If you want a tinker thing and have Windows 10 ... doesn't that now have the Linux subsystem?
If so, a better option for your tinker site might be this:
https://docs.moodle.org/311/en/Installation_guide_for_Windows_using_WSL_(Windows_Subsystem_for_Linux)
Big advantage to that approach ... you have to install Ubuntu Linux first before everything for Moodle and that means your tinker site will be almost the same environment as what most have for hosting a moodle remotely.
My 2 'sense' of course! (Nope! That's not a typo but 'play on words'!)
'SoS', Ken