I checked the Apple TV support page, and they don't list any specific players as supported. That surprises me, as there's no question that many channels won't work on every device, in particular devices over 5 years old. Your 4200 was released in Mar 2013, so I'm amazed this channel works at all.
I haven't logged into ATV on my 4800, and my iPhone on my personal account is upstairs and powered off (I usually only carry my work phone), so I can't get the authentication code to test it for you. Of course, I don't subscribe to TV+, I just use it as one of several libraries I can access my purchased titles.
This old Roku 3 4200 has been a trooper! There is literally no channel that does not work with it.
Netflix profiles are fine, Prime Video works with profiles, Hulu is flawless. The only channel that shows "age" is the Kanopy app, which sometimes stutters to fill in titles while scrolling through the list.
The only Rokus I have had to give up on are the old Roku2 HD/XD/XS (no Netflix profiles) and the Purple Streaming Stick (3500)
Yeah, my 2 XS players have long since retired. They couldn't even keep up with YouTube, but kept freezing up.
I agree that the Roku 3 is a fantastic player, but as mentioned it's really getting old. I was just looking at the hardware specs on the Roku developer's site, and it was the first with a dual core CPU and accelerated graphics. Dual band wireless, Ethernet jack, USB port, it has all the good stuff. Still, I expect it to be dropped the next time Roku declares more devices as legacy and will no longer be supported. They've dropped support for first and second generation players, and yours is a third generation. They newest players are considered 9th generation, so they've come a long way.
I did finally give in and got a 2021 Roku Ultra on sale for $65. What an upgrade. Everything is lightning fast now, and I have Airplay support.
Now, what to do with the old Roku 3?
