If a team does not turn up with enough players for a game and they cannot play then the other team wins the game. This is called a 'walkover'. So, if people think a team will win in a walkover it means that will win easily.

Example: It should be a walkover for the Premier League team against the non-league side.

Here's an example headline from Talksport:

Senegal stripped of AFCON title as Morocco handed walkover victory in astonishing ruling

A walkover victory is given when one team fails to play the game. The other team wins a walkover.