Mac OS Yosemite: downgrade a new-to-me machine to Mavericks?

I was offered a nice deal on a used Mac that has a fresh install of Yosemite.

Unfortunately there’s an app I MUST use on this machine that seems to not be Yosemite compatible and is no longer updated by its mfr (it’s known-good under Mavericks).

The instructions for downgrading that I can find online assume that you had a machine with a Mavericks installation and you’re now trying to downgrade back to that Mavericks installation.

Is there a way I can take a new-to-me machine with Yosemite and install Mavericks on it? I haven’t bought this used Mac yet but I would like to if the answer is yes.