Glitch re: being asked to login when user hasn't even used a free credit yet

Not sure how this happened, but someone I sent my app to had an issue. I believe she clicked on button 2 (which is a link to an external page explaining the app) and then, when she returned to the main app page, she couldn’t use the free messages I’ve allowed there. Here’s what she wrote:

“I tried to use a free message – but when I clicked return it said I had to login with a username and password.  I don’t have an account. Don’t know what I am supposed to put there.”

This seems somewhat serious to me as it could turn someone off, leading them to click away from the app.