Entity picks up item, player gets an archievement (HELP)

I've been trying to make an archievement, where if a fox picks up a cookie the player that dropped it gets an archievement, but I don't understand how to do it, I've managed to figure out how to make that when an entity picks up a cookie a player gets an archievement, but I don't know how to make minecraft know that this entity has to be a Fox, and the player has to be the one that dropped the cookie, I've been looking for tutorials and in the forum but everything seems so complicated, HELP PLEASE QWQ!!!
(I don't know anything about how to code or make mods qwq)

I'm really really new on the platform, and I've been searching and trying for hours, please someone help me

If it's any useful information, I'm making a mod for forge 1.20.1, and I'm trying to make a procedure to add it into a new archievement

And sorry for my bad english I really am tired rn