"mllbb for b-associated production, 2 tag, mA 700 mH 540" of "Search for a heavy Higgs boson decaying into a $Z$ boson and another heavy Higgs boson in the $\ell\ell bb$ and $\ell\ell WW$ final states in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector"