Google translated that *very well*
I installed Moodle in the class room, but did not know how to install so that visitors can take the test without having to register or log in.
Its not really possible. It was talked about in this forum post:
https://moodle.org/mod/forum/discuss.php?d=342178
To summarize, the best way is to provide sample username and passwords on the front page for your site visitors. eg user01 / Freetest-2018