Earning achievements.

How do I complete the 2 objectives involving the Voidbringer in Wayne's final mission?

I defeated the Voidbringer on January 16, 2022, and received both achievements. I had to fight it 3 times.
1) Void Destroyer (kill it while it's in the Void Circle, while you are outside the Circle) - I managed to reduce its health to 400 while it was in the Circle; the final blow was dealt by Fate Weavers, the number of which I increased to 120 using reinforcements (with this setup, combined with the "Perfect Strike" ability, they could deal about 900 damage). But leaving it with less health than the power of the Fate Weavers' shot requires some trickery. It worked on the second try.
2) Old Man, I Remember You (rescue 3 units from the Void Gate) - it uses this ability when it is not in contact with anyone, so I just didn't get close until it used the gate three times. They are cleared with 2 hits from large units.

Added 6 minutes later

I'm having trouble with the "Satellite" achievement series; the goal is to complete the official campaign map with a hero. I'm playing on maps, but nothing happens. How do I get them?

The "Satellite" achievement series requires completing single maps (scenario or skirmish) with Necromancers, Nagas, Demons, Orcs, and Dark Elves. For Humans, it seems that only the scenario (Princess Varna or Wars of the Throne) counts (but I might be wrong). I collected these achievements by completing scenarios for Humans and Nagas, and skirmishes for Necromancers, Demons, Orcs, and Dark Elves. Using a campaign hero is not required anywhere; you just need to start with the castle specified in the achievement description.