Mastodon GO! currently only runs on a Mastodon server running glitch-soc.
Support for vanilla Mastodon or "unhosted" installs may be added at some point in the future.
To install, simply add the mastodon-go folder into app/javascript/themes—you may want to use git submodules to make staying updated easier.
To do this, run the following code from your Mastodon root directory:
git submodule add https://github.com/marrus-sh/mastodon-go app/javascript/themes/mastodon-go
You can then update the frontend by running:
git submodule update app/javascript/themes/mastodon-go