There were 14 bots in D.II, but 10 of them relegated naturally (6 of them finished 8th). So there were 6 live teams that relegated from D.II.
The other 4 bots from D.II and the one bot from D.I passed through on their way down to D.IV. So there were only 5 spots open for secondary promotion from D.III to D.II. The 5 teams were 1st place conference teams that did not win their playoff, selected based on their regular season record. It appears that they had 20, 19, 19, 18, and 18 wins. There were 6 teams with 18 wins, so it appears you missed out on point differential.
I think this will be fairly typical pattern from now on. If a team goes bot in D.II it will be more likely that the team isn't doing so well to start with. Most D.II teams that go bot will have some FA players, and will suffer because these are their star players. And even if they don't lose any players, they will be predictable for other experienced owners in D.II.
In D.III there were quite a bit more bots that didn't relegate, and add in all bots from D.I and D.II, you get 30 extra promotion spots. Plus about 1/2 of the leagues in D.IV are all bot, so they had a team promote to D.III and then were instantly relegated.
It appears that the threshold for secondary promotion from D.IV to D.III was a 2nd place finish with 17 or more wins. I think that in past seasons, some 3rd place teams had promoted.