Try npm install <ghusername>/<repoName>, where <ghUsername> is your GitHub username (without the @) and <repoName> is the name of the repository. That should correctly install it. You will most likely want to use the --save or --save-dev flag with the install command to save dependency in your package.json.
If that isn’t working correctly, check the contents of your .npmignore file.
Don’t panic if the install command takes a long time; installing from a git repository is slower than installing from the npm registry.
Edit:
Your problem is that in your case, dist/ is not committed to the repo (since it is in the .gitignore). That is where the actual code lives. dist/ is built from the files in src/ before the package is published to the npm registry, but dist/ is never committed to the repo.
It’s ugly, but in this case you will have to remove dist/ from the .gitignore and then run:
npm run build
git add .
git commit
git push
(Ensure that you have run npm install first)
You then should be able to install from github.
There might be another way to do this using a prepare script, but I’m not sure if that’s possible; I’ve never tried it. Edit: Cameron Tacklind has written an excellent answer detailing how to do this: https://stackoverflow.com/a/57829251/7127751