Step1

 Go to Office.com -> Products -> For enterprise to get 30 Days Trial Account, choose MS 365 E3

We'll find the below Interface

Step by step we need to follow all the Instructions until we activate the E3 Trial License.

Then, for 1st Time Login with the account, need to Go to Office.com portal and we will have to go through below steps to finally reach at the Admin Page:

Now the below is How the admin.office.com portal looks when we visit for the very first time:

Once we Click on Show all in the Left panel, it'll display All Admin Centers as below interface, which means, these are all the Admin Roles which can be performed as a Microsoft Admin:

Hence, from above we can understand that, a Microsoft Administrator can be assigned with One or Multiple Admin Roles, depending on his position. We'll discuss about Each Admin Role thoroughly, to get familiar with each Admin Role.