Make Nextcloud local machine install point to my server

When I try to [Add Folder Sync Connection], I cannot get the option to select my own remote destination folder. All I get is [-]Nextcloud [+] <folder icon> @Home.

Yet the Nextcloud snyc set up window is showing [Connected to https://<my domain name / folder> as <my username>]

There must be a parameter I've missed. What is it?