Did you build vcv yourself also or use the download version? And did you build the GitHub plugin in the toolchain?
There’s a problem that rack built on arch raw has a different libc than the toolchain and you either need to use arch both or toolchain both. (You can get the toolchain rack by downloading it).
(Read more Neither SurgeXT nor VCV Free plugins are installing/updating in VCVRack (Arch Linux 6.3.x) - #51 by relyt29 here )