Streaming HBO?

Hi there!

So after being a tv-less household for decades, I finally broke down and purchased an inexpensive Smart (ha!) TV, a Vizio Model E241i-A1w.
It streams Netflix, Amazon Prime, Youtube, etc just fine from my iMac, and I picked up an older used Philips home theater/DVD system for a song at St Vinnie's which actually sounds pretty decent.

So all is well, except when I went to (unrelatedly) turn in my rental cable modem after buying a new one, they talked me into a faster internet package (my main interest, after all) that included free HBO. So I took home the cable box - but when I just went to hook it up, the cable outlets in the room turned out to not be cable outlets but old-school speaker wiring.

SO.. my question is this:
If all I want to do is access the free HBO, are there any alternatives to installing a new outlet in the living room or running a long cable from the cable modem two rooms away? Is there an inexpensive way to stream this in the same manner as Netflix, etc, from my computer? I love that the only wiring is for power and between the TV, DVD, and speakers.

Thanks in advance for any advice or thoughts!