I'm trying to follow a YouTube tutorial, but when I put a playdate.update function in, it keeps doing this:
Sorry I can't post a link! The website won't let me!
Did you compile your game with pdc? It looks like you're just running Lua code with the VS Code extension. If you haven't already, you should check out the Inside Playdate webpage.
(By the way, I don't know whose tutorial you're watching, but in case you're not watching him SquidGodDev does a great job explaining how to get up and running with the Playdate SDK!)
How to compile with pdc?
I highly recommend you visit https://play.date/dev/links/ and look at some of the SDK tutorials there, I don't think the tutorial you watched did a very good job explaining how to make a Playdate game 
Fixed it myself! Turns out I just didn't know where to store my games! Eventually, I discovered that following this file path: C:\Users\username\Documents\PlaydateSDK\Disk\Games
leads to an empty Games folder, perfect for storing my games! 