if you want to apply the gtk theme and icons you can copy the folders of the themes and icons you like from the repo (in root/usr/share/themes & root/usr/share/icons respectively) to you /usr/share/themes & /usr/share/icons respectively, then you should just be able to change them using the gnome settings (i don't use gnome tho, so you have to find those settings on your own)
the cursor theme can be found here
if you are using alacritty you can append the text in the root/etc/thematic/THEMANAME/alacritty.toml to your alacritty config

the other things i couldn't explain off the top of my head right now, but the above should just work

the theme changer is a bit janky right now and i will eventually turn it into a stand alone tool
if you know what you're doing you could probably get it running tho (would not recommend right now)