Welcome.
You can make this happen with a true / false property.
i.e. staff? = true / false ( if it’s one user type, than it’s not another )
This should take care of your relationship concern as well.
Try learning / finding your Adalo answers by using the documentation and university, before asking the forum. If you need an example similar to what you’re doing with multiple users… try to follow a “marketplace” tutorial. or uber, or Airbnb clone…
Happy building.