Adjective used to describe the state of activities performed in relation to a corporate or private network, typically via a VPN. When onlan, internal resources are available, as one has a connection through a VPN. Interestingly, depending on the setup of the VPN, offlan resources--such as public web sites--may be inaccessible.
Sorry, but the files you want are only available onlan. You'll need to connect to the VPN to download them.