Parsec doesn't list a minimum network speed for clients/guest we imagine the faster the better and probably nothing with download speeds below the host minimum upload speed.
PC's running windows 7 cannot host Parsec sessions, but they can be clients
2. Getting Started
First simply download the Parsec software https://parsecgaming.com/ and run the executable, the installer will ask if you want to install controller support, click yes to this.
Next create an account and login.
You can add friends by their Parsec user name, they will need to install the software and create an account if they don't already have one.
The player intending on hosting the game will need to enable hosting in their Parsec client.
Guests can connect by either clicking on the friend who will be hosting and then clicking "Play", or the host can invite people by sharing an invite link.
When everyone is connected the host can simple run Brief Battles either via steam or the DRM-free executable and the game stream should be visible to everyone connected. Players can now use their controllers to send input to the host and play the game.
For more setup tips visit https://support.parsecgaming.com/
Host should turn off fullscreen and run in a 1080p borderless window if possible, this improves framerate on guest machines reduces input lag
Reducing the resolution in Brief Battles will also improve the framerate on guest machines
If inclined you can rent a cloud computer to run brief battles to take the load off one machine having to be the host