Newman doesn't run when scheduled

My question:
Trying to schedule (on a Mac) some calls using either Automator or launchd that runs a shell script that calls the Postman APIs. When you run the shell script manually from Terminal, it runs perfectly. However, if you run it from Automator or any scheduler, Newman which is used doesnโ€™t run at all, it silently fails.
Any insights to making this work would greatly appreciated.

Thanks