The 3Dsellers Facebook Store is no longer available, so it cannot be added to a personal profile or a business Page.
To send Facebook visitors to your eBay listings, copy your link in Marketing > Webstore > Facebook Page and add it to your business Page's Shop Now button, as explained in How do I link my Facebook Page Shop Now button to my Webstore?.
Connecting a Meta account for Helpdesk messages or the catalog is a different feature: see Connect Facebook and Instagram (Meta) Accounts.