Hi William,
It seems you're trying to access content from your iPhone from your Mac. We can work together to find the info you need.
First, please make sure you're using the same Apple ID on your Mac that you do on your iPhone. That is key to having content sync between your devices.
If you're on the correct Apple ID, you can redownload purchases as seen here:
Redownload apps, music, movies, TV shows, and books - Apple Support
If it's that you took videos on your iPhone you want to view on your Mac, one option is to enable iCloud Photos:
Set up and use iCloud Photos - Apple Support
Good luck!
Thanks for using the Apple Support Communities.