iMovie on Macbook Air cannot open movie made on iPad Mini 6

I created a movie project in iMovie on my iPad Mini 6. I need to edit it in iMovie on my Macbook Air, as the functionality on the iPad is inadequate (as usual). I sent the project to my Macbook via Airdrop, but when I try to import it into iMovie on the Macbook it's greyed out - it cannot be selected. Does anyone know why this is happening? I at least expected that I could work on a project across two Apple products.

My iPad is on IOS 17.6.1; my Macbook is running Sonoma 14.6.1.

Thanks for any advice!