Viewing Collections in LrC

Since I got my new Mac Book Air last year, I cannot view my Collections in LrC saved to my portable hard drive. I can create NEW collections, but I cannot view the ones already created. My old computer was a Mac Book Pro. Could that be the problem? I keep LrC up to date. Thank you!!

By @charlotte_6168

Collections cannot be saved to a hard drive.

If you still have the catalog file from before you got your new Macbook Air, the collection are in there. Sounds like you didn't transfer the catalog from old Macbook to new Macbook Air properly. The correct steps (if you have the old catalog file) are here.