Moaform does not require respondents to register or log in to Moaform to answer. If they are asked to log in, they have accessed a different URL other than the answer URL, possibly form editor URL for a creator.
When you have finished editing the form, click the 'Collect' link at the top center of the form editing screen to go to the response collection setting page. After checking various settings here, click the ‘Start’ button at the bottom of the page and you can see a answer URL. If you give this URL to respondents, respondents can respond directly from PC or Mobile without having to sign up or log in.