definition,
Hab area - an indoors room filled with proper atmosphere(O2 & pressure etc.) can support lives
EVA area - i cant breath in here

steps,
1. build a room & fully covered with roof, give power & atmosphere support(put an air outlet)
2. the room should have a double airlock with at least 1 empty space in between, set up the EVA suit stations in the room(not in the air lock corridor)
3. this room is ur "Hab area", set an area 100% covered all the room space(not including the wall & door), in here we name this new area as "area with O2" for example
4. choose all the EVA suit stations, set "at" to "auto rest", set "Hab area" to the area "area with O2"
5.select the pawns which u want to release to outdoors, mark some EVA time slot(red color) for them in the "Restrict" menu
6. if it is not working, delete all the areas and re-do it from step 1
7. always make sure the "area with O2" is 100% covered all the room space(not including the wall & door), especially after u expended ur Hab area