SailPoint Identity Security Cloud's API lives on your tenant at https://<tenant>.api.identitynow.com. Trade a personal access token's client id and secret for an access token first.
Create a personal access token under Preferences → Personal Access Tokens. The token call returns an access_token used as {{SAILPOINT_TOKEN}}; {{TENANT}} is your tenant name.
Full reference: https://developer.sailpoint.com/docs/api/v3/
curl -X POST "https://{{TENANT}}.api.identitynow.com/oauth/token?grant_type=client_credentials&client_id={{SAILPOINT_CLIENT_ID}}&client_secret={{SAILPOINT_CLIENT_SECRET}}"
curl "https://{{TENANT}}.api.identitynow.com/v3/accounts?limit=10" \
-H "Authorization: Bearer {{SAILPOINT_TOKEN}}"
curl https://{{TENANT}}.api.identitynow.com/v3/sources \
-H "Authorization: Bearer {{SAILPOINT_TOKEN}}"