When calling HOPEX REST API you need to provided the absolute identifier of the environment and the repository. You will find below some explaination on how and where to find this information.
In HOPEX V3 on the server side you can access the :
You can find the ID converter in the installation of HOPEX V3. Default location is C:\Program Files (x86)\MEGA\HOPEX V3\Utilities\HOPEX Server Supervisor
Should you not have it you can use the attached file to this post. Simply unzip and launch the executable file.
To get an detailed explaination watch the following video