Missing addoninfo.txt, server cannot mount addon.

Create addoninfo.txt and add the following text:
"AddonInfo"
{
"title" "Bloody Winter"
"description" "Simple objective map in style of surviving for 10 minutes."
"version" "1.0"
"author" "NaVy"
"authorSteamID64" "76561198000514489"
"type" "map"
}

Hello NaVy,

ZPS has been updated to 3.1 and a few changes were made that affect your map:

- Some textures are missing due to the update as some base textures were moved.
- Some models seem to be invisible/missing.
- The entity item_healthvial is now item_pills
- The barricade system changed. Barricade hammers are a melee weapon that require ammo to place boards. A separate entity, item_ammo_barricade or item_ammo_barricadepile, has to be placed within the map now.
- All movable prop_physics/prop_physics_multiplayer entities are set to breakable by default now. So stuff like blue shelves or couches will need to be set to unbreakable in the entity's options.
- Workshop addons require the addoninfo.txt in order to play the map. There is a ZPS guide on Steam with info about this titled "[W.I.P.] Creating maps for ZPS 3.0 and above" (its at the end of the guide).

These are just some of the things that currently affect your map that I noticed. There might be more that I did not see.