I'm on holiday at the moment so reopened the app to transfer photos from my camera directly to my phone again after a while of not using it (at home I just use the microsd card readers in my computers). Anyway, I discovered Canon now has a mandatory account requirement. There wasn't even an account option when I bought the camera. Luckily the old apk from APK mirror still works on my phone.

You'll want to keep a copy archived for reverse engineering if/when Google decides to prevent these "loopholes".