Authentication apps work separately for agents and users.
This means that if you want to add the same user source for agents and users, you have to install it for both of them. You will need to use a different configuration for each app, since you don’t want all your users to be able to sign in as agents.
Note that once an agent has signed in, they can use the portal regardless of any user authentication requirements.
For example, if your users have to sign in with their Facebook accounts, whereas your agents use normal Deskpro accounts, a signed-in agent could view the portal without needing to use a Facebook account.
Agents using the Log in as user button function will still bypass any user authentication.
Remember that if you connect a source to authenticate agents, all user records from that source will be turned into agents. Do NOT create more agents than your license allows. If you accidentally create thousands of agents, it can cause serious issues with your helpdesk.