I can't figure out how to enter the R+D room even though I have the R+D key. On the map, I go all the way to the east where it says "R+D", but I see no door to unlock or enter. I destroyed the turret next to the "high voltage" sign that's next to the unbreakable window, but I don't see any other way to get in. Did I miss a step?

What you missed is about half the level. Keep exploring.

I've visited the Cryo and Science Sections, the Medical and the Crew Quarter Sections, but I can't find an entrance to the "R+D" Section. I see a marking for it on the edge of the map in the east, but when I try to go over there there's no entrance. Does a special event have to trigger in order for me to get access to that section?

Update:
I think I finally found it. It looks like the map wasn't updating and that's why I couldn't find it. The R+D entrance is located south-east on the map.