Ranger – “Defense” [Campaign 5, Mission 3]

I don't know what the problem is. I did play it in version 1.0, but with a licensed copy. There were no glitches. The sequence is as follows: we capture the first castle (I don't remember about the losses, but I remember that it was practically without them). Then we buy a second hero and leave him with ents (so that they don't slow things down) in the castle. The rest of the troops are bought as they grow, but, as far as I remember, only ents are enough for defense (it needs to be checked). We sail with Fedor to the mainland (the big island?), capture the castle (elven), then release the land hero, then capture the necropolis castle, and release the dungeon hero. Next, we max out Fedor on chests and monsters and buy an army in the starting city. That's it - the scenario is completed. It took about three weeks in total. This is off the top of my head, I don't remember exactly, maybe it's less (or maybe a little more), but I managed it with only the starting army, so it's definitely possible to do it even faster. I didn't level up the released heroes at all, but I maxed out Fedor.
P.S. Difficulty - the second to last. I haven't tried it on the hero difficulty.