Dear - There should be numerous users have access on your vCenter,Can you tell me - Is this error triggering to all when they have tried to create a VM, this is just to confirm if there is any permission issue.
Other hand can you tell me clearly - Are you trying to create a VM at cluster level or Host level or Datacenter level, this is just to check if the below specified error is same for all cases or not,
And here are you using any already provisioned disk to create a VM or creating now with new disk.