How do I add the customer portal feature to my Dynamics?

So I have been researching and many sites are saying that in order to add the portal to your CRM you need to login to the admin portal which I do. Then go to admin centres and choose Dynamics 365. 

Now here is the problem I don't have the option 'Dynamics 365'. Is there something that I need to do or is there some sort of different option?

I'm on the Dynamics 365 Plan 1 so surely I should have access to the portal?

All help is much appreciated.