No - no problem. There is certainly nothing complicated here.
It looks like the PayPal add to cart buttons are straightforward coded links direct from a PayPal account.
Remember if you want to recreate/duplicate this then make sure you download a copy that can go back if you make a hash of it. The important thing is to use the exact same filename ‘library-f.html’ so that anyone that has bookmarked that page will not get a 404 error when returning to the site.