macOS may require permissions to be set for Serato Studio to access your Music app's 'media library', once the Show iTunes Library preference is enabled, under Setup > Library

If you don't allow this permission you may not be able to successfully import the library from the Music app on your Mac (formerly known as iTunes) into Serato Studio.

You may also see the following error message:
 

If you've disabled the permission previously, you may not see the error message above, and your media library may not import correctly, or at all.

Enable Media & Apple Music permission

To resolve this, navigate to and enable the following permission:

System Settings → Security & Privacy → Media & Apple Music → Serato Studio

In some cases you may need to add the relevant application, before it can be enabled, by clicking the + button, and locating Serato Studio.