For Ravenbloom Conservatory, opponent moves into that open bf. I play Ride the Wind to move my unit into Ravenbloom where he is attacking. Do I get the "when you defend" trigger?

No — you don't get the trigger. The battlefield has no Controller during the Showdown, so "you" in "When you defend here" refers to no one, and the ability stays dormant.

Control is only established at the end of a Showdown (Rule 348.2.a). Since Ravenbloom Conservatory was open (uncontrolled) when your opponent moved in, it remains uncontrolled while Contested — even after your Ride the Wind brings a unit in as the Defender. "You" in a battlefield's ability refers to its Controller (Rule 190.6.d), and with no Controller, the "when you defend here" condition can't be met by either player. This is the exact interaction covered by FAQ #8647, just with the roles flipped.