This script is for 2.79. You're trying to load it in 2.80. If you want to set up Maya nav then check this vid. It's for 2.79, but is applicable to 2.80. https://www.youtube.com/watch?v=12fqTUyDts0
SSssoooooo, I have 0 clue how the hell Blender works, hence me coming here looking for a keymap that actually makes sense from a Maya user perspective (and every other DCC...), so I just went to properties and imported the python script, but got a handful of errors: It just goes offscreen, so idk what it says.