SageCM API help

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Hi All,

I have been trying to test the API with Postman, but just can not get the Token. 
Have gone through https://api-ext.sagecm.intacct.com/ but still getting a {"error":"invalid_client"}. 

I assume the https://api-ext.sagecm.intacct.com/token is the correct URL but not sure. 

Has anyone successfully been able to do this? 

Any Help will be greatly apricated. 

Shane