The simplest way to get user information from Office 365 is to get all users with the Get-MsolUser command, like this:
Get-MsolUser -All
This will bring back a collection of every user in your tenant, which may take a while if you have a lot of users. Here's an example of the output:
UserPrincipalName DisplayName----------------- -----------thomas.carpe_liquid-hg.com#EXT#@liquidhgdev.onmicrosoft.com Thomas Carpeincrediblemeh_gmail.com#EXT#@liquidhgdev.onmicrosoft.com Eric Carpe (MS Account)eric.carpe@lab.liquid-hg.com Eric Carpebeowulf@lab.liquid-hg.com @AppPool Beowulfalara.rogers@lab.liquid-hg.com Alara Rogersbender@liquidhgdev.onmicrosoft.com Bender B. Rodrigueztcarpe_colossusconsulting.com#EXT#@liquidhgdev.onmicrosoft.com ...