Template Changer won't install (using Flatpak version)

OS: Linux Mint 21.3 Cinnamon
LO: Version: 24.2.5.2

I downloaded Template Changer from here: Template Changer » Extensions

Then I tried to install it through Libre Writer by clicking Tools > Extensions > Add.

The following error appeared.

image

And when I exit from that error (but not when I press ok), another appears:

image

I tried creating a folder within the location stated in the error, then added the template-change oxt file there.
It then appeared in the extensions list in LO, but still wasn’t working.
I then tried to add the oxi file (from downloads) again, and I popup appeared asking if I was sure I wanted to replace it. I pressed yes, restarted, and it was working, albeit a new location/file has been automatically created in the uno_packages cache.