Install NodeJS from https://nodejs.org/en/download/
Install Github Desktop https://desktop.github.com/
On the page https://github.com/olenakozdoba/hackathon-project find green button "Clone or Download", click on it, then click on the button "Open in Desktop". When the GitHub desktop is opened, click "Sync" button. This should download sources to your computer.
Open command line window, run "npm install -g bower", command should run without error. If "npm" command is not found, try restarting computer.
Change location to local working copy of downloaded project (i.e. <...>/hackathon-project/easy-charge), run command "npm install". Command should finish without error
Change location to "app" subfolder. Run command "bower install".
To run app locally, from "app" subfolder run command "polymer serve --open". This will open browser window with default url "http://localhost:8080/" and map should show up. Keep command line window open and don't stop the running "polymer serve" command. After modifications in html, js and css files are ready to be tested just switch to browser and reload the tab. changes should be reflected. If not, try clearing cache.