Try this:
1.) Once the project is on your machine, open cmd/terminal and run:-
For cmd
npm install -g npm@5.6.0
For terminal
sudo npm install -g npm@5.6.0
2.) Verify the npm version once it is installed by running:
npm -v
This should print out 5.6.0
3.) Enter the project folder via your command-line and run
npm install
4.) Then run
ng serve
Your app will run without any compilation errors.