Hello.
The article, which you found describes a later period (1940)
Enlisted personnel and junior officers in the Red Army had no sleeve patch. Only buttonholes on the collar.
Buttonholes have color depending on the military unit, which served the holder.
Infantry - crimson, edging on three sides - black.
Medical military unit - dark green, border - red.
Insignia placed on the collar. For non-commissioned rank indicated by a red triangle with gold trim.
From left to right, top - down:
petty officer
section commander
Junior platoon commander
Private soldier