Sign in to the MyNetDiary web app with the Sign In With Apple button. Go to Settings > My Account > Create Account, enter a valid email address and password, and save. Then open the MyNetDiary or PlateAI Android app and sign in with that email address and password.
If you have created MyNetDiary or PlateAI account and used Sign In With Apple option to log into MyNetDiary, PlateAI or Web app, you can sign into this account using an Android app.