From the guidelines:
Definition
Some items, especially banknotes, tokens and notgeld, are issued by an entity (bank, company, chamber of commerce, moneyer, etc.) different from the government of the state and from the mint.
It is only when an item bears the name or logo of, for instance, a bank or a company which is at the origin of its issue, that this entity is considered as an issuing entity. Any institution linked to the coin or note but not represented or named on it can be described in comments, but not in the “issuing entity” field.
The Mint that made the medal goes in the Mint field.