I know there are several BO3 maps released for custom zombies, how come i don't see any here? i know this isn't a proper post but it's pretty much the only one so i hope to clear some confusion

No maps have been officially released. The mod tools just came out to the public, and the very select few have only been working on maps for the past couple months. A fully detailed, polished map will take a fair amount of time to finish entirely.

That said, there are a couple maps that, even though stated as WIP, are very clean, polished, and practically done. One of these is Fabrik der Untoten by Madgaz.

All maps and mods will (most likely) be released on the steam workshop page, instead of here on UGX. When maps get released fully, some of them may appear on the UGX finished maps section. However, not all will. A website like this isn't necessary for sharing maps anymore, as its through steam now.

They are all on the Steam Workshop, thats really the only place you can download them

Most people on here that are making them haven't finished them yet.

A lot of the good maps(not box maps) on the steam workshop are from people who had the alpha and have been working on them for a while.

The reason they aren't already finished is probably because they actually want to make a good map.