My browser / operating system: MacOS Macintosh X 10.15.6, Safari 14.0.1, No Flash version detected

So, I have a problem where I make an animation on my PC, and I make sure the timing is just right. And then later I watch it on my iPad, and the timing is all messed up. So my animations only run correctly on Windows. This is an especially big problem since I just started doing lip syncing in my animations.
I’ve also had Mac users report to me that the timing is wrong on MacOS as well. Is there a way I can have my animations check whether the project is being viewed on Windows or MacOS/IOS? Thank you.
My browser / operating system: MacOS Macintosh X 10.15.6, Safari 14.0.1, No Flash version detected