I've searched the internet for way too long now trying to find how to do this. I want to get into speedrunning but can't find how to downgrade my game to the right version. I know it's probably really easy to do but I really need some help from you professionals. I don't know if this is the right place to ask.

Guide and resource section have a link to it, as well as the discord. For future reference, if you're looking for something related to any speedrun, search in resources provided by the community first before you search the generic internet.

Affirmative, big chief