I was wondering if it would be possible for users to put in their steam64id for the linking process? This would be an alternative to doing it in-game.
If this is already possible please let me know.
Thank you.

There needs to be some part of the linking process that is in-game so we can confirm the user is who they say they are. This is a security measure so other players don't link with accounts they don't own.

Okay, the only reason I wanted this was to automate adding players to the whitelist if they are in the discord. Thanks anyways.