The same thing happened to me too and in fact I have been commenting on it these days, that the guides they showed did not work.
It turns out that you have to follow the steps indicated by G-bo on the main page, where you download the latest version of the mod and version 5.2.2.
In these steps it is indicated that you have to install the latest version of the mod, if you have progress without logging into Facebook (that is, saved on the device) you will have to go to the settings where you always save manually, and click on new game.
Once you confirm restarting the game, exit immediately and delete the latest version mod, and install version 5.2.2
It's complicated to explain but, it turns out that when you do that, when you enter version 5.2.2, the mod this time will give you the option "later" since you don't have progress on the device and thanks to that you don't The message about just updating will appear, as has happened to many of us, since you have restarted your progress on the device and you have to create your avatar again.
It is now when you have to connect your account to Facebook with version 5.2.2 of the mod and you can log in easily.
After that you have to simply update the mod to the latest version again, without deleting version 5.2.2 of course.
2 IMPORTANT THINGS
1. You have to have an account already connected to Facebook in the official play store game previously to be able to log in to the mod (I assume you know this but just in case I'll warn you).
2. I recommend that you change the clothing and hairstyle of your avatar in the Facebook account already created, before doing this entire procedure.
Since it may cause an error when connecting to Facebook in version 5.2.2, put him in the simple tunic from your Hogwarts house, remove all his accessories and give him an old hairstyle.