I'm guessing there's content in it that PDFs don't support anymore.
You might try printing it as a PDF. If there's video, it'll turn into an image.
If it's a web project and you click Share, you'll see a Print option. Click that and set Destination to Adobe PDF.
If it's a social media post with animation, you can click Share, create a link, open the link, and right-click and select Save video as...