Press 'Multiplayer'
Press 'Add Server'
Enter the server name and address (play.modernbeta.org)
Press 'Join Server' - you're done, have fun!
Press 'Play'
Press 'Servers'
Scroll down and click 'Add Server'
Enter the server name, address (play.modernbeta.org), and port (19132)
Press on the server entry we just created
Press 'Join Server' - you're done, have fun!
Make sure your console and phone are on the same internet/wifi connection
Go to the app store and download 'BedrockTogether' - or download 'MC Server Connector' alternatively if BedrockTogether doesn't work for you, they work basically the same
Open the app and enter the server IP (play.modernbeta.org) and port (19132) - then click 'Watch Ad and Run' - Wait for the Ad to finish
On your console press 'Play'
In the 'Friends' tab you should see 'LAN Games' with the BedrockTogether server you started, join it and you're good to join!