Apple Users

I've been using Mac Office on my Mac laptops since Office for Mac 2003. Mostly Excel and Word, which I use daily. I can't recall any problems opening prior versions (or PC versions) of any of the apps. I should note I don't use the Office 365 subscription software. I purchased the software itself, with lifetime license for both my PC and Mac -- 2003 versions were discs I bought with the laptops and more recently my 2021 Office versions were downloadable software through the MacWorld Shop. I mention that as I'm not sure if there is a difference in how the lifetime license vs subscription versions act with files, although guessing it's the same?

Anyway, that initial 2003 version lasted me through several laptops until I got the newer Mac with the M1 chip at which point I upgraded to 2021. It was a pretty seamless upgrade. The only thing is that some of the older files have the old xls, doc, etc. extensions. I can open them though, no problem, and then I can save as xlsx, docx, etc. filetype.

I also move files between my PC and Mac without issue.

Just to make sure, I just now found an old .xls, .ppt and .doc file on my mac and opened each of them. They opened just fine.

Hope that helps.