Sorry to hear that you are facing issues in installing XD , Could you please share us the mac OS version and XD version you are trying to download . Please add a screenshot of your mac details and error message your seeing.
If you are running Windows, Xd needs UWP, i.e. Windows 10 in order to run. Not sure what OS you are on, but it's unlikely that it's because of the CPU. I remember seeing the "Incompatible" thing when trying to install Xd on an older machine with Win7.