How to use editor on unsupported OS - you can try virtualization ...
Windows 7 users
1. install Windows 10 as virtual machine (client) into VMWare Player program (free for personal use)
2. Install Rig Manager inside Win10 VM.
I haven't try this yet with RM, but every piece of the software on the planet i tried is working inside VM. Virtualization is a very reliable solution.
On Mac, or as alternative to windows VMWare, you can use free VirtualBox virtualization software.
edit: haven't checked VMWare Win7 host compatibility, sorry, maybe you'll need older version of VMWare player or find other virtualization software, which is Win7 host compatible.