Hi Marie Loerakker,
Yes, it is possible!
You can control based on user role eligibility.
For that particular input widget --> You will have visibility section --> When selected --> You will be able to see the user role (Refer the screenshot).
You have Roles R1 and R2
R1 have Enumeration - E1
R2 have Enumeration - E2
Add 2 enumeration and apply visibility conditions based on user role.
Hope it helps!
An enumeration is a fixed list of values defined in the model.
What you want to achieve is to select out of a list of dynamic values.
Therefore you need a reference between the entity to which you want to link the user and the account entity. Next you need a reference selector in your page, where you can select one of the users over this reference.
I recommend that you take the Rapid developer course online first:
and especially this module, where you are introduced to references (associations) and reference selectors: