It sounds like you may have missed a step in the installation. Did you do what is directed in https://webwork.maa.org/wiki/Installation_Manual_for_2.18_on_Ubuntu#Install_Dependencies?
To check this run "perl -MMojo::SQLite\ 9999". That should return
Mojo::SQLite version 9999 required--this is only version 3.005.
BEGIN failed--compilation aborted.