The on-line check-in link on DVCMember.com takes you to My Disney Experience (MDX) to complete the process. If your reservation does not show on MDX, you will need to link it manually.
Main MDX website:
https://disneyworld.disney.go.com/plan/
MDX is only for the resorts at WDW. If you are staying at VB, HHI, or Aulani, you can use:
MyDisneyReservation.com to complete the on-line check-in process.
On-line check-in is not available for the DL resorts.