Can I install Mac OS from another account? I have two new Mac minis, which have Sierra installed. I need to install Yosemite and El Capitan on them. However, there is no old versions of the OS in the App Store.


Can I download old OS from some old account that has these versions in the App Store and install on my machine?
If yes, is this legal?
Can I use same installer on more than one machine? Is this legal?
Yes, if one of your account do has the installer in the Purchase list, you can download them and use it on your Mac Mini. However, you can’t just install it on top of Sierra. You needs to wipe the drive or use a separate partition.

If you downloaded the installer, it’s perfectly fine to use it on multiple machines.