gotcha, i just played it last night and i got the same issue. after i waited a bit they spawned in like a big wave not sure why thats happening but ill look into it

i know i mean when i spawned pressed the radio nothing showed up im using a mutation that makes it so im playing it with myself no bots

there should be a radio on the stage next to the machine gun turret that will start the spawning

where are the zombies i cant spawn any

updated you can find it now in addons

Game does not appear in addon section of survival, if you want to play for now you can open console and do
changelevel hanover_survival

I will fix this issue soon