Access to old photos on MacBook Pro 21

If you migrated an old iPhoto Library to a new Mac, note that the "iPhoto" app was discontinued in 2015 and replaced by the "Photos" app.

You can import the photos from your iPhoto Library file into the Photos app. Open the Photos app, go to the File menu an click Import. This will import the photos but not the album or event structure. Also see information in Import from another photo library on Mac - Apple Support

Do you have any Photos or iPhotos libraries on the computer? They are usually in the pictures folder.