Managing a organization's members

I am working with an NGO. We use the unpaid version of teams. I am the technology manager for the organisation. I did not create the organisation. But I work in close collaboration with the person who did. 

Is there a way for me or the person who created the organisation to see a list of members of the organisation. (not a list of the members of a team)

I believe I can do this using the Admin Center (correct me if I am wrong)

I cannot access the admin centre as the email used to make the organisation is a personal email.
It asks for work or school email.