The quiz results page has a drop-down disguised as a button at the top left - by default it says Grades. If you instead select Responses you get a display containing all the students' submitted code, which you can download as a csv (or other). Is that sufficient for your needs?
There's also a script in CodeRunner, downloadquizattempts.php, which is pretty much a database dump of all quiz submission info. See https://github.com/trampgeek/moodle-qtype_coderunner#administrator-scriptshttps://github.com/trampgeek/moodle-qtype_coderunner#administrator-scripts. But it is liable to exceed some of the php.ini settings for your server with large classes - you might have to talk nicely to a sysadmin to get it work OK.