There's a learning path for the native REST in Mendix:
As well as documentation that I personally found very handy when I started with it; Consume a REST service:
And publish a rest service:
This documentation is for Mendix 7 btw since you said you were on 7.23
Your question is a bit too undetailed to properly understand where you go wrong with your problem.
It looks like you're on the right track using the Call REST service action.
However, you should use http://**********/rest/api/***/Token in the location field and add a header with Key=Accept and Value=application/json
This is my configuration of the REST service but it´s not working, I get this errors when I try to use the microflow: “An error has occurred while handling the request. [User 'Anonymous_50cfa956-9fe2-42a8-b9f8-645f8b937f29' with session id '9d877653-XXXX-XXXX-XXXX-XXXXXXXXb51d' and roles 'Administrator']” and a Client Error.