@meetdilip How can I work with PWA to get that push notification service

Plez help me , I just read about PWA , such a beauty it is.
My basic problem is when somebody post a question in category mentioned in my website , A person should get notification .

This is my AIM , but what i wanted to know to get this thing working with nodebb

@pitaj how to check that , URGENT HELP REQUIRED

error: NodeBB could not connect to your Mongo database. Mongo returned the following error: failed to connect to server [127.0.0.1:27017] on first connect [MongoError: connect ECONNREFUSED 127.0.0.1:27017]
4/1 06:07:32 [2416] - warn: NodeBB Setup Aborted.
MongoError: failed to connect to server [127.0.0.1:27017] on first connect [MongoError: connect ECONNREFUSED 127.0.0.1:27017]
at null.<anonymous> (/home/ubuntu/workspace/node_modules/mongodb/node_modules/mongodb-core/lib/topologies/server.js:327:35)
at emitOne (events.js:77:13)
at emit (events.js:169:7)
at null.<anonymous> (/home/ubuntu/workspace/node_modules/mongodb/node_modules/mongodb-core/lib/connection/pool.js:274:12)
at g (events.js:260:16)
at emitTwo (events.js:87:13)
at emit (events.js:172:7)
at Socket.<anonymous> (/home/ubuntu/workspace/node_modules/mongodb/node_modules/mongodb-core/lib/connection/connection.js:177:49)
at Socket.g (events.js:260:16)
at emitOne (events.js:77:13)