You can use a tool such as Postman to send the request to the server.
The request needs to be sent to the admin port as configured in the modeler.
When configuring the request you need to authenticate with a password and the line you posted explains where to get the password if you are running locally.
EDIT: I have used the process explorer to see the system variables of a running process - https://docs.microsoft.com/en-us/sysinternals/downloads/process-explorer
Havent tested this on the cloud
The one you want:
The authentication failed can have several reasons, Two of them I ran into:
=> each time you do a new deploy "run locally" a new password is generated.
=> you have to encode the password you retrieve from the process explorer e.g. using https://www.base64encode.org/