Granting access to the web application for external Office365 users

Hi, I managed to develop multi-tenant web application in Active Directory.
Everything works smoothly for my directory users and for external directory users with Office365 and Azure subscription.
I was wondering if it's possible to grant access to users who have only Office365 and admin is without Azure subscription..?
Is it possible? I mean I don't know anyone with only whatever Office365 subscription and before starting test account for Office365 I decided to ask firstly.. =]
If there is no way to do this, does someone knows the workaround? =P

Thanks in advance!
Kamil