When creating a MongoDB destination, you can choose the host, port, username, password, and database, or provide the full URI connection string.
For more information, go to the official connection guide.
Hightouch requires identifying one field as the document main identifier. Usually is the _id field, which is autogenerated by MongoDB
if not provided, but you can choose any other field. Be aware that you might need an index on that field to speed up the sync.
For mappings, you could send every column as a field in the document, or choose mappings that allow you to filter and translate to the field
names you need for your documents.