When you add a Watched Folder, Roon opens its folder browser so you can navigate to where your music lives. This article explains how to find and select your existing music folder in that browser, and what the New folder button actually does.
Open Settings, then Storage, then click + Add folder. The Choose music storage folder browser opens. It has three parts:
Roon watches everything inside the folder you select, including its subfolders. You don't need to drill into the deepest folder; select the top-level music folder instead.
New folder creates a new, empty folder inside your current location. Clicking it asks for one thing only: a name ("Please enter the name of the folder you wish to create"). It doesn't open a folder, it doesn't accept a path, and it won't help you navigate to music you already have. To add an existing music folder, browse to it and click Select this folder as described above.
New folder is useful when you want a fresh destination for music, for example, creating a Music folder on your Nucleus's internal drive before copying files to it over your network. For that workflow, see Nucleus internal storage.
If you've browsed to where your music should be and it still isn't showing, please get in touch with our Technical Support team here and include the device running Roon Server, where the music is stored, and what the browser shows.