The device you sent me to not only doesn't do 4K @60hz, it isn't HDMI 2.0a, and also doesn't support Dolby Vision. ETA: the second comment is that it doesn't support HDR/Deep color so the customer returned it for a refund.
***Edit to add clarity: my first post was about having to buy a new receiver. If you didn't buy your receiver this year (or one of the like 4 last year that supports HDCP 2.2 over HDMI 2.0a) you're probably going to need a new receiver. If you have a fairly new receiver, the bitstream signal over optical/spdif would have worked fine and you could just have plugged the Apple TV into your new tv's HDMI 2.0a port and the audio into your not so new receiver that most likely has support for Dolby Digital +, etc. Apple chose to not output bitstream audio over optical/spdif, probably because of Siri integration (but you could PCM the same way but over optical imo), and thus requires you to use HDMI to connect to your receiver. If you try to use HDMI 2.0a with HDCP 2.2 on anything but the latest receivers you won't get anything on your new 4K tv because it won't pass through.
This is the only point I am making about the Apple TV 4K