I am pretty sure they are talking about TVs, but they want COMPOSITE inputs. The red, yellow, and white plugs. So you have the right idea. They do have boxes like that for HDMI to composite (and RGB), too.
https://www.bestbuy.com/product/insignia-hdmi-to-rca-converter-black/J2FPJK9G8J/sku/6633030
I have one of these, myself. Just make sure the RCA side is the OUTPUT, and not the INPUT. They make both, and the analog to digital converters are more common than the digital to analogue ones.