could not connect with the world

Hello, the problem I have is with version 1.16.200 and it is that I cannot play with a friend in his world, I get unable to connect with the world and so all the time, I saw videos and tutorials that creating and deleting worlds there were possibilities that I could enter a game, but it didn't work for me either, that means I bought minecraft without being able to use it... I hope someone answers me and not a bot, thanks.... I use direct wifi, my friends share the Internet from one mobile device to another, does that affect anything?