Here is the Free Game Champions Leaderboard.
Those who have completed www.unknownfiles.co.uk/freegame so far and submitted their names are:
1. Musha Soturi
2. Anon (B)
3. Craig Johnson
4. Steve Jenks
5. Virginia R. Hall
6. Chris Harbour
7. Chloe Rewaj
8. Thanning (B)
9. Anon
10. Katie Piatt
11. Elizabeth
12. dirtysock47
13. Escape Room In A Box
14. Jake
15. Lockandcode
16. MarthaandMartha (B)
17. Alex (B)
18. Daniel
19. Drux
Ok, so I've sort of hit a brick wall with the five notes on youtube, being tone deaf. I might try to brute force the answer because I sort of hear the first four notes are going down the keyboard whilst the fifth is like the first - so something like D-C-B-A-D....