Missing Media

Hi all

I recently purchased Adobe Rush to edit videos for my business. I upload the videos from my iphone and when I try edit them on my Mac I get a large red screen with an exclaimation mark. I did some research and paid to by Iskysoft video converter to convert my videos to MP4 (I saw somewhere that it could be the iphone video format). This has not worked, my iphone gets a message saying "missing media" Please help, I am out of options here and I am not great at all the IT terminology.