I want to show my survey onto a special (Facebook) group to test my survey if the questions are right, if there are not unneeded questions, and so on.
The answers given by the test respondents are not important, also I don't want to know their email address. I want to give a URL of my survey, where people can fill it.

At this moment, I thought I had set it right, but the preview asks first name, last name and email address.
What did I set wrong?

Regards,
Guido

You have set it up for public registration. As it is just for test, when you activate it, don't go for the closed mode (with tokens).

If you don't go into closed mode, by default anyone who has the link to the survey can access it and fill it out.