Valid within Disney property but off property you will need a temporary one from the State of Florida: From the govt website:
Handicap Placards for FL Visitors
If you are visiting Florida from another U.S. state, you can use your home state placard for disabled parking in Florida.
If you are visiting from another country, you can apply for a temporary placard. You will need:
A copy of your disabled parking permit from your home country.
A form of identification, such as your passport.
Payment for the $15 fee.
Take these items to the nearest Florida DHSMV tag office or tax collector’s office.
OR as Minnie mum just stated she never had a problem