Found a way to get to that invoice, finally
Login to https://www.apple.com with your login credentials
On the top right corner click on the basket/shopping bag
It may show ‘empty’ but click on ‘Orders’
It should show ‘Products you’ve ordered.’ and show your ADP order there as ‘Arrived’
Click on it to get the details
On top right corner it will show Order number, order date and ‘View invoice’
Click on ‘view invoice’ et voila…