/bin/bash /home/myuser/PirateBoxScripts_Webserver-master/piratebox/install.sh
This also corrects a wrong path on line 47 that was causing the install script to fail.
/bin/bash/ /home/myuser/PirateBoxScripts_Webserver-master/piratebox/install.sh
Also line 36 and line 47 where pointing to incompatible launching path (the first was in PirateBoxScripts_Webserver-master/piratebox, the second just in PirateBoxScripts_Webserver-master/).