You can only connect other collections properties if that collection data is available on that screen. Like if you are coming from a screen that has a list and then if that collection has a number property you can connect that property on this screen’s slider! If you are coming from a screen clicking on a button then you don’t get any data expect if you make the button a list and coming to this screen. In there you need to create the record and then link it to this screen and then you can update that record in this screen!
Or the easy solution will be create a number property on the Users collection and then connect that to the slider and on the create action add that logged in user’s > number property to that field and clear that property after creating with a update action.