Before running anything pease ensure you have the following properly installed in your machine.

Ruby 2.7.2
Rails 6.1
Postgres > 12

I recommend you installing rbenv to handle ruby versions, please follow the instructions https://github.com/rbenv/rbenv

Once you have ruby installed install the gems bundle and rails.

gem install bundle

gem install rails

Clone the repo, then run inside the root folder of the repository.

Install the gemos for the proyect

$ bundle install

Install the javascript dependencies:

$ yarn install

Setup database:

$ rails db:create db:migrate

Run the server:

$ rails s

And in another shell, compile the assets (JS and CSS) with the command

$ ./bin/webpack-dev-server

If all went well, you are ready. Go to http://localhost:3000