User creation in Skype and Exchange Hybrid environment

Hi,

First create a AD user on-premises. Activate that mailbox on-premises and move online (if you want to). Then activate the csmeetingroom in Skype on-premises (and move to online if you want to).

https://docs.microsoft.com/en-us/surface-hub/hybrid-deployment-surface-hub-device-accounts

So yes, always create on-premises first and move the account if you want to have it in the online environment instead.