The template doesn’t work for version 6+ of mongoose .
For anyone having the same problem, please change your version of mongoose to be > 5.13.8 in the package.json , then click Run (on repl.it) and try again:
"dependencies": {
"body-parser": "^1.15.2",
"dotenv": "^8.2.0",
"express": "^4.12.4",
"mongodb": "^4.1.1",
"mongoose": "^5.13.8"
},