When adding a new user, they won't have any Services set up for them to be able to send posts, view streams, or generate reports, so if you would like this new user to be able to perform any of these actions they would need to either add new services, or have an already existing user share services with them.
If you would like them to be able to access any of the services you or any of your team members have already set up, then we would recommend you share the services, instead of having them add themselves.
This is for a couple of good reasons:
1. If you share a service with a new user, then they will have access to all the reporting data already gathered by your account, and so they'll be able to generate reports reaching back to the point you had added this service, otherwise they'll only be able to generate reports displaying data from when they added it themselves.
2. If there is more than one user managing specific accounts, by sharing services, all users will be able to see which messages have been scheduled and when.
3. Each account has a limit to the number of services they can add, so if each user adds their own services this limit will be reached very quickly. If, however, the users in this account share services they can all have access to a great deal more services.
If there's an account on a Small plan, which allows up to 3 users and 48 services, if each user adds their own services, then they can add 16 services each.
If instead one user adds 48 services and shares them with the other 2 users, then they'll all have access to these 48 services.