To start backend, ensure that mongodb is running and you have up to date c++ compiler and std library (compatible with c++11).
From /backend folder:
npm install
node index.js
To start the frontend, ensure that backend is running (it will start without, but you wont be able to do anything).
From /frontend folder:
npm install
npm run dev
If it complains that nuxt cannot be found, try node_modules/nuxt/bin/nuxt.js from frontend.
If you have your 3000 and 3001 ports open, then backend will by default run on localhost:3000 and frontend on localhost:3001 (but see starting messages for exact information).
SSL certification is self-signed, so you have to add it to chrome before you can see the pictures. We have created one certification for both server and backend (using this guide), note that on production environment you should use separate certificates signed by CA authority for your domain.
To add the current self-signed certificate you should consult e.g. this answer on stackoverflow.