Idk bout you, but you should possibly check your "My Purchases" tab on Itch, cause it should show up there...
If that doesn't work, this page by Itch.io themselves might help?
https://itch.io/docs/creators/how-buying-works#:~:text=The%20purchase%20dialog%20can%20be,click%20the%20Download%20Now%20button
