Magic URL with Deep Link URI in Flutter Mac App

I have a Flutter app for Mac with a myapp://test custom URI. If I visit that URI in my web browser, it redirects to my app.

But when I try to create a magic URL token like this:

final session = await account.createMagicURLToken(
  userId: 'test', 
  email: 'test@example.com', 
  url: 'myapp://test'
);

...I get this error:

AppwriteException: general_argument_invalid, Invalid url param: URL host must be one of: localhost, cloud.appwrite.io, appwrite.io (400)

How can I make the link in the email point to my custom myapp:// URI? 🤔