Sorry here’s a better tutorial. I might write one, it is interesting that they all suck in different ways.

https://starbeamrainbowlabs.com/blog/article.php?article=posts/237-WebDav-Nginx-Setup.html

The folder is defined by the “root” directive. Like with any other nginx setup.

Cam be anything you want, just have to install nginx and configure it: https://medium.com/learn-or-die/build-a-webdav-server-with-nginx-8660a7a7311