If it's their own content, I'd doubt that the hdmi out of a PC would have HDCP. But still, I would not trust a down-converter for this... Way to many variables for it to operate reliably.
Just a thought... Roku Express+ has legacy outputs. Very inexpensive. Put a digital sign "channel" on it. Or simply "Cast" content to it from a PC or tablet.
I'm Not an engineer, but I play one on TV. My handle is Tweety but I have nothing to do with the organization of similar name. I just had a really big head as a child so folks called me tweety bird.
