This is really just to help anyone else out who has to go through this and maybe save them a bit of trouble.
I recently bought an EOS R, and wanted to get an Intervalometer for it. I went to the Canon website and under "Supplies and Accessories" for that camera, it said to buy the TC-80N3. So I bought one on Amazon and got it yesterday, only to find out that it doesn't work. It has the old three-pin style socket, and the EOS R has something that looks like a headphone jack. After a ton of research and coming up with nothing, I called Canon. The guy on the phone was able to give me some direction, and told me that I needed to buy an adapter, part number RA-E3. It's a bit tough to find, but it's out there. I wish they'd had this information on their website somewhere...maybe they do, but I couldn't find it.
I know I could have just bought a Vello Shutterboss, but I like Canon accessories for whatever reason.
12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.