Space nick problem
Comand /lp user "xxx xxx" parent add rand
Dont work

This is not an issue as player names (not nicknames) can't have spaces in them.
So you have to use the actual player name or their UUID.

That is something that @lucko has to look into

Dont work

Could you elaborate more?

I can't give a player a rank that has spaces in the nick name (Xbox Account)

What error messages do you get?

Will probably be fixed by making sure allow-invalid-usernames is set to true in your config file.

I still have this problem. A player has a space in his nickname, for example "DAF MERKURIY", and when I try to give him rights, I get the message that the command is not recognized

/luckperms user "DAF MERKURIY" parent set donater

I also want to say that I have set allow-invalid-usernames=true, but it didn't help.

Ah, if you use uuid, everything works.

If by nicknames you mean actual nicknames given by plugins such as EssentialsX, then they won't work.
LP expects a player name, not a nickname. There is a noticable difference between those two, especially since the later is only handled by the plugin that gave it to the player.