Part 1: Atik is the first Partzuf attributed to Atzilut... In other words, it is one of the Sefirot of Adam Kadmon, as the proposition goes on to state, yet it is considered to relate to Atzilut.
Part 2: Atik is Malchut of Adam Kadmon... As already explained (see Opening 70), every Sefirah that rules on its own is called a Partzuf in its own right. Since Malchut of Adam Kadmon has a function of its own – namely, to govern Atzilut – it is therefore called a Partzuf.
...which extends with the repairs required for this... For in one place the Kabbalistic teachings state that Atik was made from MaH and BaN (see Etz Chayim, Shaar Atik ch. 1). Elsewhere, however, it appears that Atik is Malchut of Adam Kadmon (Etz Chayim, Shaar Seder Atzilut ch. 1) – and it cannot be said that Adam Kadmon was constructed of MaH and BaN. The explanation is that in order to govern Atzilut, it was necessary for Malchut of Adam Kadmon to take on these aspects (i.e. of MaH and BaN), and they are its repairs, for it is with this power that Malchut of Adam Kadmon governs Atzilut.