No Personas roles to select

Hi,

I'm configuring the SAP Screen Personas, referring to this website

SAP Screen Personas - How to configure the system (troubleshooting FAQ)

At the /N/PERSOS/ADMIN_UI I need to assign the Personas Role ADMIN_ROLE to the user. But in the setting page, Personas Role is empty. How to add the role so I can select it?

Thanks.