Moving a Lightroom catalog from PC to Mac

Something along these lines,
On your Windows PC

1. Select File then Export to Catalog
2. Select a name and location for the new export catalog
3. Wait a long time for it to copy the catalog file and all your photos to the new location.

On your Mac

1. Create a new Catalog in your desired location
2. From the File menu choose Import from Another catalog
3. Chose to either
   1. Import files and leave them where they are
   2. Copy files to another location and then import
4. Option a is quicker, but doesn’t move the files
   Option B is slower, but will move the files to another location if thats what you want.