for some reason after the first wave there is no zombies?

Yes, it’s issue of single player mode, to get full experience you need to play it in multiplayer

I consider to find solutions in near future to solve issue with singleplayer gameplay

The map and the guns are well made and what I love especially is your love to detail in the building, for example the underground section with the overriden fog ambience or the vents and how they drain oxygen so you don't camp in there are really well made.

BUT, the "Horde" gamemode is kinda, stale. I mean, you're faster than the zombies, there are no special zombies, and weapons like the flamethrower make the map a walk in the park -> way too easy.
There's also little sense of progression, since there are only 2 weapons to unlock with your keycards. Why give the player so many with so little to unlock? How about clothes that improve your speed or explosive magazines for example?

Lowered the movement speed of player, I hope it will affect on gameplay only the best way

Cool concept combining two modes together: horde and deathmatch. I haven't played with my friends yet, but I'm looking forward to that.

I agree with some opinions that this map lacks progression, here are my thoughts on how to improve:
1. More clothing and armor - pretty self explanatory. By clothing I mean some camouflage set so you can hide from other players outside.
2. Weapons mods - rn banshee has slots for barrel, grip and sight. Would be cool if there were mods that let's say increase damage and accuracy.
3. Better loot hidden deep in the base - imagine a safe that accepts 10 keycards to unlock a good armor/weapon which would make a point in farming those keycards.
4. Deployable barricades - so that we can protect ourselves from zombies and other players.