Now optimized for the incredible power of the new Mac Pro and featuring dozens of pro editing enhancements, Final Cut Pro X is the best choice for editing and delivering 4K video. Editing - Smoothly edit multiple streams of 4K at full resolution. An enhanced playback architecture paired with the power of the new Mac Pro lets you edit Multicam with up to 16 simultaneous streams of 4K ProRes.
Support Apple offers a range of support options. Please note that these steps are not intended to address a specific issue and are not comprehensive. Mac App Store Support Page Get information about finding your purchased apps, resuming interrupted downloads, backing up your app purchases, troubleshooting the Mac App Store and more.
Apple Final Cut Pro X 10.4.4 Presentation