Can't create or join realms

I'm not sure if the version is right (I have Minecraft Windows 10 but the bottom right of my screen says v1.5.3), but I've been having a consistent issue trying to join realms and create one of my own. I keep getting error messages telling me it's because of "how my account is set up," but I have looked over all my settings several times on the Xbox website and on my Xbox 360, and nothing appears to be set up wrong. I have checked every box that should allow me to do what I want to do regarding multiplayer gameplay, and I still can't join/create realms. I did manage to get on my friend's realm after she sent me an invite link, but I can't join through a game invite or through the main menu list. I also would really like to create a realm of my own, but it just won't let me. I talked with someone from Minecraft/Mojang support a couple times, but they were no help.