(WARNING: Replay code will break and unbreak at the same time and also at 13:29.0 I was AFK for a few seconds.) First, you go to the link, paste the level code in the editor, go to the finish line, play the editor, press the level select button, and it will go to level 7. Press the select button, and it will load the custom level. Copy and paste the replay code if you need help. That's all and have fun :)
(P.S. If you beat it, copy and paste it into the comments or forum and credit @TimonUbud; he did a great job fixing the replay code.) Forum Link: https://scratch.mit.edu/discuss/topic/784878/?page=1#post-8189050 (P.S.S. I will follow the first 3 people who beat the level.)