Read this
https://steamcommunity.com/app/310950/discussions/0/3342162929527161178/Forget the AE, CE is replacing it as the "unlocks everything up to now" edition.
You can unlock characters using in-game free currency, just a grind to do it. But if you are not that into fighters and don't care about skins, I would get the vanilla (which like MKXL did, updates the game to CE with stuff locked) and work towards unlocking. Depends if you want instant access to the roster or are happy playing towards unlocking a character or two that you like.