Roles cannot be connected directly to org units, because they exist only in a list view. The connection is done through the jobs. You assign the role to a position and link the position to the org unit.
You do this as follows:
Create a role under the Organization facet and the Role subfacet.
In the facet Organization, sub facet " Positions" you search or create the suitable position and link in the detail content the corresponding, suitable role under the point "Roles".
If you now select the org unit to which you have assigned the job in the Organization facet under "Graphic", you will see the position here, as well as the role behind it in the Detail Content of the position.