i cant figute it out either doesnt work alone i assume

Pavlov's singleplayer Zombies doesn't allow players to change the map. So to play Workshop Zombie map you have to Host or Join a multiplayer Co-Op lobby. If you want to play by yourself or with friends you can set it to a private game or a friends only game. The Multiplayer lobby should allow you to change the map.

Play Online
Host COOP
Friends Only or Private Match if you dont want randoms
Select map
Launch

the map doesn't show up for me when i try to select map any advise?

you have to switch to the legacy version, it was broken by the UE5 update