About users being stuck at a set level, I don't think there's anything that
@Yunana24 can do for this, you'll just have to wait for the next update and try that.
Or uninstall the mod and simply play normally for the time being, you won't be able to install the original game over the signed modded apk.
It is nothing to do with the amount of levels released in game as of yet either, even though they claim to be over 50 levels.
When game was originally released I played for free and was past this cutoff point and had places like the Christmas Town and had over half of the 87 characters in game.
Try a fully rooted device and see if you can sign in and link account, then just install normal game and play past this point again.