Edit Passes button not appearing in Wallet when no passes are available

Solution 1:

The company that runs the ticketing system for the ticket you purchased is responsible for providing a way to add a pass to wallet, usually through their app or a valid Apple Wallet link (hence how it could be embedded in a QR code). For example, an airline would have a 'Add to Apple Wallet' button in their app, or email you an 'add to wallet' link.

I'd recommend looking into whether the service you bough the ticket through has an app with wallet capabilities listed towards the bottom of the App Store product page. Otherwise they may not support Apple Wallet and then you'd be out of luck.