3.1.2.1 is the last stable edu version shared thanks to @redux, import the zip file, close ninja,
then paste and replace the EliteLicenser.dll file in ninjatrader8/bin/custom, start ninja, launch predator and when prompted for the license just
enter random numbers. The predatorXPullback also works with this method
https://workupload.com/archive/vhWTy6BHY7