After i had the issue for months, i finally found a fix:

Do the process (add to in game favorites) one time on Pc.

When the webpage turned black on the browser, a pop up notification will appear and it will get blocked. Open that pop up window and is a Maniaplanet account persmision page. You click allow and then it will work . Seems that the pop up window doesn’t show up on iOS safari, so that’s why It freezes. After is authorized it will work on Pc and on mobile