Here the word "apostleship" defines what kind of "ministry" this is. Alternate translation: "to take Judas' place in this apostolic ministry" or "to take Judas' place in serving as an apostle" (See: [[rc://en/ta/man/translate/figs-doublet]])
This phrase refers to Judas' death and likely to his judgment after death. Alternate translation: "to go where he belongs" (See: [[rc://en/ta/man/translate/figs-euphemism]])