We do not recommend attempting to use Evolve in conjunction with OwnerRez.
The specific issue with the Evolve calendar is, they piggyback on HomeAway's API calendar and provide iCal through that. So you can import their bookings into OwnerRez - sort of.
The problem is that instead of creating separate iCal events for each booking, they merge together adjacent bookings into one long block. So they can't be converted to bookings in OwnerRez as normal. If you're using Evolve, you really have to update the calendars yourself on both sides. That adds considerably to your work - they don't play together at all well.