I'll admit my situation was unique. I have a 27" 2010 iMac, maxed out at macos High Sierra. I've worked extensively with ProShow Producer, and migrated over to Creator. Unfortunately, your new Mac version doesn't work with High Sierra, it only works with the current macOS. So in a nutshell, here's what I did, what happened, and my fix... and the request for an iOS version of Creator/Director for the iPad Pro.
I installed MacOS Catalina in a Parallels virtual HD. Set my "machine" parameters, and installed Creator. Built the show fine, took a good six hours to render a 9 minute show, and then uploaded for client approval. Client had given me the wrong list of music to use, so I had to go in and re-edit. Beautiful thing? They said nothing about the slides... it was all about the music.
So... I loaded the rendered file into LumaFusion for iOS, extracted the original audio, dropped in the three new pieces of music, and was completely done with a new edit in less than ten minutes. Had I jumped back into the virtual HD to do the edits, it more than likely would've taken me an hour or so.
I'm not going to complain about not having a version for earlier MacOS options (at least back to Sierra). I'm not even going to complain about not already having an iOS version. What I AM willing to do, is point your attention to LumaFusion and see what you might take from that app.
If you ever loved your users enough to actually develop an iOS version, my wish would be to make it as simple and intuitive as LumaFusion is. Your software's already great... taking some editing tool tips for video/audio/transitions and export would be phenomenal.
Thank you for the feedback on this issue. Photopia Creator / Director for Mac are currently limited to macOS 10.14 Mojave (and newer), for a variety of technical reasons. We have looked at adding support for macOS 10.13 High Sierra, but I'm not sure if / when that might be possible.
The rendering time you saw (six hours for a nine minute show) does appear to be extreme. This could be caused by the way that Parallels environment was setup (very low RAM, for instance) or a number of other factors. I suspect that the other program was able to process that audio replacement so quickly, at least in part, because the original video stream didn't have to be re-encoded. If they were able to simply remux the audio / video streams into a new container then the video output process would indeed by very quick.
Please feel free to reach out through the Contact Us form on our website if you have any further feedback on this situation or would like assistance in troubleshooting that Parallels environment.