Hi Cody,
If you don't want username and password for Rest API, then you can try Azure AD provided that your cluster is on Azure. See https://docs.microsoft.com/en-us/powershell/high-performance-computing/hpcpack-cluster-active-directory?view=hpc19-ps for how to setup
your cluster in Azure AD. Also note that you have to use a new set of Rest API for HPC Pack if you want to use Azure AD. Here's the API reference for the new one compared with the old one: http://download.microsoft.com/download/B/D/B/BDB8782A-FAAF-457D-AF3D-0B157FEEDF4C/New%20Set%20of%20HPC%20Pack%20Scheduler%20REST%20API.pdf
Regards,
Robert