HumanoidDescription system page does not specify that Rthro mode has to be enabled for animations to be applied

On the HumanoidDescription system page, it does not say anywhere on the page that you have to enable Rthro mode (set animations to Player Choice) for your game in order for applied animations to HumanoidDescriptions to take effect on characters. I’m still a bit confused on the difference between R15 and Rthro animations so this was not apparent for me and caused me to experiment around for almost 2 hours before figuring this out.