Cannot connect to realms

Hi, I'm helping my little brother figure out why is it that he can't connect to any worlds. He's using an android phone and currently the latest version updated on his phone is 1.2.5 Beta, and everytime he clicks on a server, he's asked to sign into xbox live free however after clicking on that, he is brought to a black screen before going back to the minecraft screen, still unable to connect, may I know how can i resolve this issue for him ?

Thanks!