Solution
The whole idea of users/privileges/access has changed since Systemlink 2020 R3 release. At this point, Systemlink introduced Workspaces and Users, which resulted in change in the whole security approach.
Now, you can declare the workspace, in which the Dashboard exists and which User should have access to the specific kind of service, including Dashboards. Thus you do not share the privileges to the users one by one, you rather assign the dashboard to the workspace and enable Users to view it. Use this
Manual to get into the details.