I need to confirm that but when having trial version for ~20 days you should have access to all enterprise features. Let me confirm all that and get back to you soon!
If you want to check on what plan you’re on you need to login to your dashboard then in the upper left corner click on your tenant and then quota utilisation. There you’ll find the tier you’re on. We don’t have a doc comparing free and trial tiers.
I confirmed from Quota Utilization page, it says subscription type is free. Do i need to do anything to turn on trial version?
I shared the snapshot in the question. It says, This feature is not available for free plans. To configure a custom domain, please upgrade your account to any paid plan