Basically me and a friend are trying to play together and it didn't let me or her join each other cause it said under date client

Me and a friend were hanging out today and went to play Minecraft. Her on a tablet and me on an iPhone 7. She could play on her own server but I could not join as it said under date client. I could join servers and my own worlds but she couldn't join me. We think it's a possibility we have beta Minecraft because she is able to go onto worlds that she did not buy/unlock with minecoins.