Hi Gemma, I'm not sure what you mean by Windows Server 2016 is installed on RedHat. If it is a virtual machine on Redhat, then it doesn't matter as it is completely containerised. 

Checkout this upgrade guide - https://docs.vmware.com/en/VMware-Workspace-ONE-UEM/2209/UEM_Upgrade.pdf

just google search for "upgrade Workspace ONE UEM 2206"