regardless of what the author documents

cd ~/MagicMirror/modules
git clone the_github_url_of_the_new_module
cd  the_modulename  (exact case)
if there is a file called package.json , then do 
npm install 

then add the module config entry to the list in ~/MagicMirror/config/config.js

then restart MagicMirror
I suggest using the npm start approach on first start after adding a module so that you can debug any issues quickly, without pm2 involvement. … then use pm2 for production again

I looked for the MM folder but can not find it. It was working before I installed the module. This is what the config. looks like.

/* MagicMirror² Config Sample
*

• By Michael Teeuw https://michaelteeuw.nl

• MIT Licensed.

• For more information on how you can configure this file

• see https://docs.magicmirror.builders/configuration/introduction.html

• and https://docs.magicmirror.builders/modules/configuration.html

• You can use environment variables using a config.js.template file instead of config.js

• which will be converted to config.js while starting. For more information

• see https://docs.magicmirror.builders/configuration/introduction.html#enviromnent-variables
  */
  let config = {
  address: “localhost”, // Address to listen on, can be:
  // - “localhost”, “127.0.0.1”, “::1” to listen on loopback interface
  // - another specific IPv4/6 to listen on a specific interface
  // - “0.0.0.0”, “::” to listen on any interface
  // Default, when address config is left out or empty, is “localhost”
  port: 8080,
  basePath: “/”, // The URL path where MagicMirror² is hosted. If you are using a Reverse proxy
  // you must set the sub path here. basePath must end with a /
  ipWhitelist: [“127.0.0.1”, “::ffff:127.0.0.1”, “::1”], // Set [] to allow all IP addresses
  // or add a specific IPv4 of 192.168.1.5 :
  // [“127.0.0.1”, “::ffff:127.0.0.1”, “::1”, “::ffff:192.168.1.5”],
  // or IPv4 range of 192.168.3.0 --> 192.168.3.15 use CIDR format :
  // [“127.0.0.1”, “::ffff:127.0.0.1”, “::1”, “::ffff:192.168.3.0/28”],

  useHttps: false, // Support HTTPS or not, default “false” will use HTTP
  httpsPrivateKey: “”, // HTTPS private key path, only require when useHttps is true
  httpsCertificate: “”, // HTTPS Certificate path, only require when useHttps is true

  language: “en”,
  locale: “en-US”,
  logLevel: [“INFO”, “LOG”, “WARN”, “ERROR”], // Add “DEBUG” for even more logging
  timeFormat: 24,
  units: “metric”,

  modules: [
  {
  module: “alert”,
  },
  {
  module: “updatenotification”,
  position: “top_bar”
  },
  {
  module: “clock”,
  position: “top_left”
  },
  {
  module: “calendar”,
  header: “US Holidays”,
  position: “top_left”,
  config: {
  calendars: [
  {
  fetchInterval: 7 * 24 * 60 * 60 * 1000,
  symbol: “calendar-check”,
  url: “https://ics.calendarlabs.com/76/mm3137/US_Holidays.ics”
  }
  ]
  }
  },
  {
  module: “compliments”,
  position: “top_bar”
  },
  {
  module: ‘MMM-3Day-Forecast’,
  position: ‘top_right’,
  config: {
  api_key: ‘e40b2a1224254edcecde9ccbc165c869’,
  lat: 40.658421,
  lon: -74.299593,
  units: ‘I’,
  lang: ‘en’,
  interval: 900000,
  }
  },

   {
   	module: "weather",
   	position: "",
   	header: "Weather Forecast",
   	config: {
   		weatherProvider: "openweathermap",
   		type: "forecast",
   		location: "New York",
   		locationID: "5128581", //ID from http://bulk.openweathermap.org/sample/city.list.json.gz; unzip the gz file and find your city
   		apiKey: "YOUR_OPENWEATHER_API_KEY"
   	}
   },
   {
   	module: "newsfeed",
   	position: "bottom_bar",
   	config: {
   		feeds: [
   			{
   				
   				title: "Sports",
   				url:"https://api.foxsports.com/v2/content/optimized-rss?partnerKey=MB0Wehpmuj2lUhuRhQaafhBjAJqaPU244mlTDK1i&tags=fs/cfb&size=30"	
   			
   				
   			
   			},
   		],
   		showSourceTitle: true,
   		showPublishDate: true,
   		broadcastNewsFeeds: true,
   		broadcastNewsUpdates: true
   	}
   },
  

  ]
  };

/*************** DO NOT EDIT THE LINE BELOW ***************/
if (typeof module !== “undefined”) {module.exports = config;}

you use npm

npm reads the package.json file to determine what libraries to install.

if there is no package.json then there is no install to do.

pm2, is node process manager. it’s job is to start and keep applications ruining.