[lubuntu] Unselect software for installation on small disk

I try to install Lubuntu on a Fujitsu Futro S900 thin client. It has a 4 GB flash drive, which seems a bit small.

So I have chosen an partition scheme swap partition. But it seems it doesn't work that way. Flash drive is still to small.

It seems, there's a a lot software to be installed on installation. I haven't found an option to unselect it. What can I do to install the system only. I will install useful software afterwards.