Hello Thomas,
I think the screenshot (second one) is a bit old - and the corresponding API endpoint has moved to a different place in the Developer Tools - API Explorer.
So, assuming you can log in and access the API Explorer in Developer Tools.
https://developer.mypurecloud.com/developer-tools/#/api-explorer (if your Genesys Cloud org is US-East-1 region)
See here for the url path if your Genesys Cloud org is in a different region:
https://developer.mypurecloud.com/gettingstarted/developer-tools-intro.htmlOn the left, go to/select Users (to expand/display the list of requests related to Users API).
Then at the bottom, you should see "GET Get the list of available users".
This appears to be the same API request that was shown in your second screenshot.
See my screenshot below:
Regards,
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Jerome Saint-Marc
Genesys - Employees
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