Okay finally after a very long time of trying different things i figured it out. So first if your using it on pc, it has to be LDPlayer 9
you then need to get luckypatcher and set that up and dont update it when it asks or itll freeze
now download the original game and load it up so that it loads the data and obb
then download a file manager program and change the obb file. you can just an "i" or whatever you want at the end of the obb file so for example. com.wb.goog.injustice.brawler2017i. so leave this renamed for now and after that uninstall it
now install the mod, but dont load it up, and then rename the obb file back to the original, so remove the "i"
now go on luckypatcher and find the game, and click menu of patches, remove license verification, auto modes, and then only leave auto mode (dex) checked), apply. once this finishes, load up the game, but pay attention, as soon as you see the big yellow button that says PLAY, click it right away before the game loads and that disappears, if it disappears itll be in a forever white screen loop. if you hit it in time, it should then load properly.