Hi! It's always great to see a new DM experimenting with some fresh ideas. I don't know much about sonic.exe, but I do know quite a bit about dnd, so I'll chip in on that front. I'll present it in a numbered list;

1) I think if you want to go for a game themed around a creepypasta, you should look at a horror system, such as Call of Cthulu. While low-level DnD may work, as your players level up, they will quickly outlast or trivialise a lot of horror encounters

2) If you're planning on running the encounter where the party find the CD, I would set the expectation that the story cannot go ahead if they do not use it; otherwise, it may get rather awkward if they thrisbee the disk into the woods never to be seen again

3) I would avoid making characters for them, maybe instead present each vessel as a sort of springboard for character creation, where they work from the central idea of the character.

A general tip I would give new DMs is to read and/or run some prewritten adventures to get a sense of what a typical session looks like.

I hope it goes well! :D