I did my speedrun and uploaded it to youtube, but then when i attempted to go on the site to submit it, the only button appearing was the "filter" button and the ones to sort through categories, any help?

Head onto the "Leaderboards" tab instead to submit it.

As the default view of the game is the "Levels" tab, which is meant to show you an overview of the individual levels, but it doesn't have the submit run button.

if you want to upload a level run (a speedrun) you have to choose which "level" (which mode) before submitting. just click on the name of the mode to be able to choose which specific categories your run is in and to submit your run.