How to find the Apple Podcasts ID of my podcast?
Go to https://podcastsconnect.apple.com/my-podcasts and log in.
There you will find all podcasts submitted by you. Click on the podcast whose ID you want to find out.
Under "Mirror URL" you will find the ID of the podcast. Just copy the last 10 digits, that's your podcast ID on Apple Podcasts. Now you can take it and paste it back on Podigee.