I vaguely remember there being an option in IntelliJ a few years ago, where you could specify a "centralized" keymap repository, which would allow all team members using IntelliJ to use the same exact keymapping. This is perfect, for example, if you're pair-programming.
However, I've recently looked for references to it, and I can't find anything like that in the latest version of IntelliJ. Did this actually exist, or is there an alternate way of doing this inside IntelliJ?
You are probably referring to the Settings Repository plugin that allows you to sync any settings you store in a Git repository across different instances of the IDE. More info and instructions can be found at https://www.jetbrains.com/help/idea/sharing-your-ide-settings.html