How does spotify connect work?

Let me start by explaining the original problem: I have a marantz and sometimes spotify connect from my iPhone to the Marantz works and sometimes not, the Marantz simply does not show up in the devices to connect to from the Spotify app.
Same counts for the mobiles of my family members.

Now I discovered that when I use the spotify connect App on Homey it always works!! I’ve created a flow that connects Spotify to the Marantz and all of a sudden I can play music from the Spotify App on my Iphone

Now I wanted to create similar flows for my family members, but when starting with that I realized that I don’t remember adding in user credentials or so.
So i am wondering: how does it work? How does homey know from which Spotify account to connect to the Marantz?

Can anyone explain?

Guess you added Spotify Connect once to Homey

Maybe you remember now.?

Else remove Spotify Connect from Homey and add it again.

Ah thats probably it.
Thanks

Would be nice if I could add more than one device and then with other credentials