@Biddaum ,the simplest approach for this is using Create Record Data Resource from the UI Builder ,these data resources are like flow actions in the Flow Designer.
Add a Data resource called Create Record in UI Builder Page,
Click on Add New(+) button and select the create record and click on add and close the dialog.
Now navigate to button you have created and on the right side under events tab there is a event called Button clicked is already available click on event handler and search for execute and select the create record and click on continue
Then give the table name as sys_user_has_role and Click on edit field values and select the user as logged in user .To select the logged in user dynamically click on the bind icon which is showing in image and select @context.session.user.sys_id and select the role as sn_grc.business_user and click on apply and save the record and observe the functionality.
If my response helped, mark it as helpful and accept the solution.
