How do you accept horse offers for your “for sale” horse? I am aging it for a specific stable and priced it very high so people would only make offers. This one stable made an offer and I want to accept it, but when I click on the link it just redirects me to my horse. What am I doing wrong? And how do I accept those offers?

You put the horse up for what you agreed on on the other person buys it

The option to make a horse "open to offers" only makes it so the person knows they can message you about buying the horse. HEE doesn't have the option to make/accept physical offers on a horse.

You can privately sell a horse to a player, however you have to have an upgraded account to do so. Public sale horses are first come first served regardless if you say its for another player.