How to add group or users to Enterprise Apps in Azure using Graph API?

To assign user/group to app using Graph API you could use the below endpoint :

POST https://graph.microsoft.com/v1.0/users/{id}/appRoleAssignments
Content-Type: application/json
Content-Length: 110

{
  "principalId": "principalId-value",
  "resourceId": "resourceId-value",
  "appRoleId": "appRoleId-value"
}

Reference : https://docs.microsoft.com/en-us/graph/api/user-post-approleassignments?view=graph-rest-1.0&tabs=http

Parameters

{id}- id/upn of the user of the user

"principalId" - id/upn of the user of the user

resourceId - Id of the app, you can get it from the portal

Azure Active Directory >> App Registrations >> Select All Apps from the dropdown menu >> find your app and click on it.

appRoleId

To get the ApproleID

Azure Active Directory >> App Registrations >> Select All Apps from the dropdown menu >> find your app and click on it >> App Roles | Preview

Or using Graph

https://graph.microsoft.com/v1.0/applications/{id}?$select=displayName, appId,appRoles

If I don't misunderstand, you would like to assign users and groups for an app. And you followed this Quickstart in the portal.

There are three methods to assign or unassign users, and groups, for an app. See here:

https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/assign-user-or-group-access-portal#assign-or-unassign-users-and-groups-for-an-app-using-the-azure-portal

1. using the Azure portal

2. using the Graph API

3. using PowerShell