Thank you so much!

Airdrop/email your playground to your mac. There open the code file (NOT the playground). Then edit your code file in xcode to fix any errors. Then you can airdrop/email the playground back to your iPad.

I have created the playground for MacOS, so UIKit is not available. Thus, UIViewRepresentable and Context are not available. Is there a way to do it with just SwiftUI and SpriteKit? I am also getting this error 'fullScreenCover(isPresented:onDismiss:content:)' is unavailable in macOS. Because its a MacOS Playground Thanks!

You can right-click on your playground book file (in finder), and press show package contents, to view the inside of your playground book, which contains all of your files. There, you have to navigate to the code file that you want to edit.