At first, please make sure that your new phone is on the same OS as your old one (Android - Android, iOS - iOS).
Here are the steps that might help:
  1. Take your new phone, fully delete Idle Pet Shelter from it and clear all the accounts you've logged in
  2. Get back to your old phone and play the game for a bit, achieve some progress, and save it in the cloud
  3. Log in to the account you've played before on the new phone (Google Play Account for Android users)
  4. Install the game and try to load the save from Cloud
  5. If it still doesn't work out, contact our support service via in-app support chat or email us at support@outloud.games