After installing SamuraiWTF to hard disk the target web-apps hostnames are missing in /etc/hosts.
$ sudo cp /etc/hosts.samurai /etc/hosts
This will be fixed in 2.1.
Additionally, it is required to add the current hostname as a valid hostname for 127.0.1.1 (currently contains samurai-wtf references) in /etc/hosts, so that the execution of sudo does not complaint.
Yeah - finding WebGoat posed a bit of a challenge. I was eventually able to bring it up in my browser after tracking down the IP address in the tomcat config file. I had assumed (wrongly) that "localhost" would work. I would also recommend adding bookmarks for each of the targets to all the installed browsers. I haven't checked them all yet but Firefox doesn't have them (except under "Most Visited").
Fixed in 2.1