I would really like to speedrun the game Archvale (not the demo) but I can't because my account isn't 7 days old yet so I can't submit my request to add the game :( please help me!
We can't help you with that, record the run required to submit the game, read all the rules, learn how to retime your runs and runs of other people, and request the game when your account gets old enough.
The best cure for your account not being 7 days old is to wait 7 days. You can still speedrun Archvale in the meantime, and there's no rule against submitting old runs.
Also, the fact that the demo has a leaderboard means there's a decent chance that someone either has requested or will request the full game soon. So keep an eye on the list of recently added games.
To increse the chances of your game being accepted, add one more social media to your profile, take your time to optimise the game and maybe even find an interesting start to show the potential of the game, do a lot of research and try to get a long run for the submission