Microservices / custom connections are really problematic to use at the moment.

To test if they actually work, you need to create it, then enable it (which is a multi-step process), then write a API call in Deluge then call it. 

You should be able to:

1. Identify if an access token has been generated within the connection prior to this

2. Actually see what the output of the token request is (similar to Postman Echo). Each connection has its own nuances and you could see what assumptions etc Zoho Creator is making about the synatax of the request

3. Be able to amend the request while the connection is still live. Periodic rotation of passwords and API keys is best practice and can't be achieved through the current interface.