Hi Ramon

To further what @heg said:
I have written an FAQ on this topic that includes download links here:
https://www.moviestudiozen.com/doctor-zen-faq/525-install-older-version-apple-quicktime-movie-studio-vegas-pro

You may also run into a 2nd problem when editing video from an iPhone.
iPhones record video using a Variable Frame Rate.
Traditionally most video editing programs only support Constant Frame Rate video.
Unless I have forgotten, I'm pretty sure VMS16 does not support variable frame rates yet.

If your video does anything weird in Vegas, I recommend you convert the video into Constant Frame Rate before importing into Vegas. If you did that step, you also wont have to worry about .mov format not working.

I have a tutorial for how to convert video with Handbrake here:
https://www.moviestudiozen.com/free-tutorials/miscellaneous-help-tutorials/595-handbrake-v1-1-1-beginners-guide-for-best-video-export-settings

Regards
Derek