In order for a person to be accessible in the Infinite Campus OneRoster API (and thus synced to RI) the person needs a User (Portal) account in Infinite Campus.
For documentation on creating user accounts, review this documentation. To create user accounts in bulk, review this documentation.
To verify if a person has a user account, search for the user in Infinite Campus. If the person has a username, they have a user account. In the example below, Amelkin, Federique has a user account but Freda, Irene does not. Consequentially, Freda, Irene will not be accessible to Clever via the Infinite Campus OneRoster API. To add a user for a person, click Add User.