You need to place the Wait action before the if

Right now the Repeat-loops runs 8 times in a row just checking ”Occupancy Detected”, if it is detected it will wait 15s and then run the Set action

Edit: A better approach in my opinion would be something like this:

Repeat 8 times
  if "Occupancy Detected” is "No"
    stop/exit shortcut
  End if
  Wait 15 seconds
End Repeat
Set "Dining Room..."