Step 1 – Open the Ableton Theme Folder
Click on the shortcut in your downloaded bundle (Or copy the path above on this page, and paste it in the address bar in File Explorer).
From here, navigate to:
C:\ProgramData\Ableton\"YOUR ABLETON VERSION"\Resources\Themes\
Test if the path/shortcut works. It should open the correct folder with the default Ableton themes, like this:
If the shortcut works:
Simply copy your new downloaded ".ask" file, and paste it into this "Themes" folder.
If the path/shortcut DOESN'T work:
You have to manually find the "Themes" folder, and copy your downloaded ".ask" file into your Ableton's "Themes" folder.
(it should be under "/ProgramData" by default if you've installed Ableton officially. If it's not, you'll have to search around.)
Step 2 – Open Ableton, and Change Theme
Open Ableton
Press CTRL + , to open settings (Or, go to "Options" at the top of Ableton, then press "Settings" at the bottom of that menu)
Under "Themes & Colors", click the "Theme" dropdown, and select your new theme.
Congrats, you've now successfully installed your new theme!