Collaborating with Lightroom Classic

I'm not sure what directions you were given, but this can't be done. Lightroom Classic does not support multi user, and a catalog cannot be shared over a network. The best you can do is each have your own catalog with a separate set of images, and then merge the catalogs when you are both done.

Curious to know the advice you did receive from support. More details?

It is not possible for you both to access the one catalog concurrently.

My thoughts would be to-

1) Select the Saved Book Collection

2) Export as a Catalog, choosing to create Smart Previews.

3) Share this 'exported' catalog with your colleague, noting the following-

If your colleague is 'local' - share the catalog on an external drive that you can pass back and forth from one to the other and edit independently (never at the same time.).

If distant apart then use a file sharing method (dropbox?) which has inherent problems with 'Downloading, editing, uploading' each time one person wants to edit the book in the shared catalog.