Roblox Auto Assign Members On Team based on if they are staff?

Greetings, I have 2 problems I need to solve, read below!

1) Hello, how do I make a script when a member of the group (5587698) joins the game and gets put into the team Walmart Staff the minimum rank to be put in there is 21 and above. If the player is lower than 21, they get put into the team Customers

Also, I need help where to put the finished script at, so it will always work, without any script errors.

2) I also have another problem, I'd like a SendNotification script with the GUI when a Super High Rank joins the game, everyone in the server will be alerted on their bottom right. (With their profile picture as well)

Thank you,

Adaaks