How to open a file created in excel4node in Meteor or save it in Meteor-CollectionFS?

Question

Node.js

I create an .xls file with the excel4node library
https://github.com/natergj/excel4node
and I need to send a link to the client to download it, how can I do it?
started working with the Meteor-CollectionFS library
https://github.com/CollectionFS/Meteor-CollectionFS
But I don't understand how to add the created file to the collection