I had a look at it now, it seems a bit sketchy... Riseup uses the bitmask VPN application so if you go to https://bitmask.net you can find out more about it. It appears to be part of the Leap encryption project, you can download it for android or Ubuntu Linux. I downloaded the Android version to try it on my phone. The download is version 0.94. I downloaded the devs signing key also from bitmask.net but open key chain says it is revoked. So I just installed bitmask without verifying it I might not do that on a PC but I don't really care about this phone. Anyway bitmask v0.94 didn't work it threw up errors when I tried to connect to riseup. So I had a look at the built in help and everything with a copyright date on it is years out of date.