and not worldbuilder save on public map.anyone know why this is?

Yes, the solution is somehow easy.
If you look at the worldbuilder file with notepad/wordpad, you can see, that 18 players and teams (0-17) are mentioned in the file.
With a 50 civs dll, you have to add the numbers 18-49 to the worldbuilder file.

i use the map a s a part of a mod.is that the only way i can add the 50 civ ddl?

Yes, the only way.
Just try it, it's really not complicated ;).