There are several problems. As @Wo3Dan pointed out in his reply, the geometry for the door needs to be in the same context as the geometry for the walls. That is, you need to open the group for editing before drawing the rectangle for the opening. Your screen shot shows heavy profile edges around the rectangle you drew for the opening which proves the rectangle is not in the same context as the wall. Since you removed that rectangle I’ve drawn two. The one on the left is drawn like yours was outside of the group. Note the heavy profile edges. The one on the right was drawn while the wall component was opened for editing. Notice it has thin non-profile edges.
You can see when the rectangle is drawn in context with the wall geometry, Push/Pull works just fine to create the opening.
Before you can add the opening you’ll need to unlock the group. The red outline indicates you’ve locked it.
Also before you go any further you should fix the tag usage. Currently your model shows you’ve been using tags incorrectly. Untagged should always be the active tag and all edges and faces should remain untagged. Only groups and components should get other tags. Remember tags do not separate geometry. You must use grouping for that.
I fixed the incorrect tag usage and got this:
Added the file after fixing the tags issue and purging unused stuff.
building a house.skp (360.5 KB)