Hello @MojangSupport my friend is experiencing issue with realm my friend me cannot join in her realm

Can you let us know which platform and version (Java or Bedrock) does your friend play Minecraft on, and what troubleshooting steps she's tried so far to address this issue? ^FF

You'll only be able to crossplay if you're on Windows 10/11 (Bedrock) edition. If you're on Java Edition, unfortunately, you won't be able to play on Bedrock realms. If you are on Bedrock, then can you let us know what issue you're seeing when you join the realm? ^FF