Trying to create a service appointment app and before using CDKDrive Appointments v1; looks like I need to get Authorization tokens. Machine to machine auth is ideal for my use case, so going with Client Credentials Flow per documentation.

Here is what my Postman request looks like:

POST URL is https://identity.fortellis.io/oauth2/aus1p1ixy7YL8cMq02p7/v1/token

PARAMS are grant_type=client_credentials&scope=anonymous

HEADERS are 'accept: application/json' 'authorization: MY_APP_KEY:MY_APP_SECRET' 'cache-control: no-cache' 'content-type: application/x-www-form-urlencoded'

Getting this response from the API instead of auth tokens; What am I doing wrong? Please help.

{ "errorCode": "invalid_client", "errorSummary": "Invalid value for 'client_id' parameter.", "errorLink": "invalid_client", "errorId": "oaeP5BBq0prT-WZ5AaYW4Rl9g", "errorCauses": [] }