Download MongoDB from their site. Here's the link for Ubuntu. https://docs.mongodb.com/manual/tutorial/install-mongodb-on-ubuntu/
Launch the installer.
After the installation rename the folder as mongo.
Change the folder directory by moving it to home directory (prefered) or to any directory you like
Make a new folder named 'mongo-data' in the same directory as mongo folder. This folder will contain the data of mongoDB.
Move to the directory where mongo and mongo-data folder is placed in terminal.
cd ~ if directory is home else cd
Then move to the mongo/bin directory in terminal.
Command : cd mongo/bin
Then run this command to run the mongodb server ./mongod --dbpath ~/mongo-data
To run the project just run this command in your command line 'npm start'