Download OS Image

Vivid Unit comes with Debian operating system pre-installed, usually you don't need to install system by yourself.

However if you want to re-install the system, or want to install a different system (if available), you can download the system disk image here.

Debian

Debian GNU/Linux 11 (bullseye) + RetroPie

MD5: 86dd3cd81e1474880b455dfc41b23792
SHA1: cc1df6a419a53c6fb3b4b1d6b9e5417e759e20c8

You can find more details about how to install system here.