Assigning users row level security roles

I've created some roles for users within Power BI desktop but I can't find how to add users to the roles.

Once I log on to the service and go to the security page, I a message telling me that RLS has moved to Power Bi Desktop.

But once in the desktop I can't see where to add said users to roles already created.

I looked at the turotial ( https://docs.microsoft.com/en-us/power-bi/service-admin-rls) which says You cannot assign users to a role within Power BI Desktop. This is done within the Power BI service.

So now I'm just confused.