Create Stack_Box_Slot for each new Element of Array

Hello everyone,
I want to create an UI that lists all the players as soon as the spawn in a vertical stack box.
I have an array of all players where new players get added after they spawned. The spawn event also triggers the update of the ui where I want to iterate through this array again and create a new stackbox slot for each player so that the list does always contain all players.
If somebody could help me with a script that adds slots widget to something like an overlay or canvas it would be really much appreciated! I find this whole update widget and ui topic very confusing…