You can also use Docker to start a Cosette development environment console that has all the right dependencies setup. From the Cosette directory, run:

docker run --name cosette --entrypoint /usr/bin/fish -v $(pwd)/:/Cosette-Dev -ti shumo/cosette-frontend

You can connect your local emacs to the development environment with:

emacs /docker:cosette:/Cosette-Dev/hott/library/UnivalentSemantics.v

If user started Docker on a different machine, you can connect your local emacs to the development environment with:

emacs "/ssh:user@machine|docker:cosette:/Cosette-Dev/hott/UnivalentSemantics.v

Make sure your emacs has ProofGeneral and docker-tramp installed, and enable-remote-dir-locals must be set.