@Tarun Saini I have been trying to download all the pages within the Adobe Express file as videos (MP4). All of them, except for the first one, download as a black-screen MP4 file. I've tried downloading them all at once and each individually – neither option worked. I also tried duplicating the file and deleting the other pages to save the animations - but the same error occurred.
I found a workaround of re-uploading the PDFs individually per page and re-animating the graphics from there individually. Hoping this is just a bug with the system or to get advice to troubleshoot if I encounter this issue in the future. Thanks!