Problem calling Writer from Books to merge and download

Problem calling Writer from Books to merge and download

Hi,

I'm building a function in Books which calls Writer to merge data into a document. I found
zoho.writer.mergeAndDownload(<document_id>, <output_format>, <values_map>, <connection>)
which is recognized in Books custom function editor. https://www.zoho.com/deluge/help/writer/merge-and-download.html

However, I can't find a way to create a connection (last argument).
The documentation sends to https://www.zoho.com/deluge/help/deluge-connections.html
which mentioned Books as an allowed service. But where am I suppose to create the connection ? In Books, under Integrations, I can't find a way to connect with Writer.

Am I missing something to merge and download ?