openmw.org

What specifically is your OneDrive issue? OpenMW's supposed to work if you've got your Documents folder in OneDrive (as that's the default for Windows 10, so it'd be pretty crap if we couldn't cope with that). You should probably create a new thread to discuss your specific problem as this one was dead for two years before you revived it so probably covers a different problem.

motaboy wrote: ↑14 Aug 2017, 16:58 2. Download OpenMW for your system (for example OS X / Windows). Install it and choose the path of your original Morrowind.esm

Would it be possible to elaborate on the bolded section in this step?

With Windows it's easy, doubleclick in the .exe-file.

But what if you download the .tar.gz file for linux? How do you "install it"?

If it's the generic Linux binaries rather than the source code (which is also available in a .tar.gz), just extract it somewhere and run the binaries it contains. You might be better off using the Flatpak release, though.