Alternatives for MemberPress?

Hello,

I am creating a site which will be accessible to members, only after choosing a pricing plan –> making the payment(other than basic user) –> registering and –> approval by admin.

I have across a MemberPress as a good option for the same. But the same is a paid plugin, and I first want to build a prototype.

Hence is there a free version plugin, with just the above basic functionality, like MemberPress?

Kindly suggest.

Thanks