Ideas portal to support single sign on for basic AD

We allow our partners to use single sign on.  it allows them to get to zendesk, ftp site and other portals of ours.

We use Azure AD Basic for this which is free and internally that allows our employees single sign on for aha.

We would really like to implement the ideas portal but it really needs to support single sign on using Azure AD Basic.

Right now we'd have to upgrade to Azure AD Premium 1 which provides

''Self-Service Group and app Management/Self-Service application additions/ Dynamic 

and there is a $4 per user per month cost, so it'd actually cost us more than aha! to do this.

Currently in Azure there is an app which allows single sign on for aha itself, as I understand it, we'd need something similar to support single sign on for azure AD Basic.