First you need to create the SailPoint Identity as mentioned by @iamology. Then you can trigger AD account creation using automatic role assignment and create account in specific OU and add it in required SG group.
To create an Identity you need an account added to the Auth source. You can do this using the following API:
Once account is added, you can run an account aggregation using the following API
that will create an identity with “USER” access
Now use the API from above post to promote the identity to ORG_ADMIN.
After this you can create an account in AD using birth right role, Identity lifecycle state, or a workflow