Polycom Trio 8500 Zoom Room certificate issue

We are trying to use 8500 as a Zoom Rooms Controller, but we are getting a Security Warning: Untrusted Server Certificate (attached a pic).

Software version is: 5.9.4.7038, freshly upgraded.

Zoom list their root certificates here - the main one is already in UC, but not the intermediate one: https://support.zoom.us/hc/en-us/articles/360044092031-Conference-Room-Connector-TLS-Certificates

Is it possible that this is the issue? If so, how do we install the intermediate certificate? The instructions found online are extremely difficult to understand. For example here:

https://documents.polycom.com/bundle/trio-sfb-dg-5-7-1-AA/page/t-ucs-sfb-install-a-certificate-for-polycom-trio-systems-using-configuration-files.html

It's not clear for us what the application profile and how it releates to the Zoom Rooms mode on the phone.