On January 10th, 2022 Pottermore sent out the following email to everyone that had purchased eBooks from their site:
The Pottermore Shop stopped selling ebooks and audiobooks in September last year and we will soon deactivate the Pottermore Bookshelf.
This means that your digital books from Pottermore will no longer be available to download after 31st January. If you haven’t already, please download and save your books before that date.
Unfortunately, we don't have access to their records or any digital versions of the eBooks purchased on Pottermore.