Floor of "цокольный этаж" must be under "уровень земли" by half (maybe less, but not more). It's "Semi-basement" in english.
"Этаж" with level of floor above or equal level of ground is the first one.
According to state rules: Министерство экономического развития
"Этажность" includes "цокольный этаж" if it's ceiling is above level of ground more than 2 meters.

Your picture looks like "Этажность=4 + подвал. Цокольного этажа нет."