Notice that WDW just recently issued:
As we plan for the reopening of our Walt Disney World ® Resort Hotels and Theme Parks, it will be important for guests to link their upcoming resort reservation and/or ticket to My Disney Experience as soon as possible. This will enable them to receive important communications and information about next steps and key planning dates, including the recently announced Theme Park reservation system.
Walt Disney World
Disney Urges Guests to Link Tickets to My Disney Experience As Soon As Possible Ahead of Theme Park Reservation System Debut
June 16, 2020