Creating a PBI tenant for customer.

Hi, every customer I've had so far already had set up the PBI tenant, set up by their IT partner.

Now is the first time the customer is looking at me to set it up. But I think I still need their IT partner? I believe the Admin of their O365 subscription needs to set it up and then also create an Azure AD account for me and assign a PBI license.

From what I understand so far there are two ways:

1. go to app.powerbi.com and create a PBI account with email address of their tenant. 

2. This one is more vague to me: O365 Admin rolls it out for the tenant. 

With first option I don't think you obtain a managed tenant with global Admin settings for multiple accounts? For example if [email protected] signs up, it won't enable him to start a workspace and collaborate with employee2 who signs up after him/her? And how would it be decided who gets Admin rights? 

I think I need option 2. 

If the it partner is unfamiliar with this as well, how do I instruct him? What is a short step by step? 

Goal is to have a managed tenant which customer can continue to manage after im done, take ownership of datasets and workspaces and use gateways. 

And could I also set it up myself despite not being the 365 Admin? Would that also earn me partner points to activate new customers? 

Beginner question despite being experienced lol, just first time customer doesn't have it set up already.