Yes, they can be used on both the desktop (Windows/Mac/Linux), as well as the Android version of FPV Freerider Recharged.

First download the levels to your computer.

Then you need to put them in your FPV Freerider Recharged data folder. The levels need to be in the correct folder in order for Freerider to find them. The data folder is named as followed:

Windows:

FPVFreerider_Recharged_Data

MacOS:

FPVFreerider_Recharged.app/Contents

(If you are uncertain of the folder location, save any level (even an empty one) in the level editor and take a note of the full folder path that is displayed after saving is complete).

Note: The name of the custom level .txt file needs to be the same as it's folder name for it to be recognized.

You can find this and more info in the user manual.