Teamcity NuGet Server APIkey and package storage

1. What is the default APIKey for nuget push?

I tried to push a package manually into the Teamcity NuGet Server without providing the APIkey, it prompt ask for user name and password. I tried to insert my Teamcity login, but it does not work.

2. Where is the packages are located in the TeamCity Server, could I maually copy those packages into that directory?

Thanks.