You need to fill out your full name but it's not marked with a * as

required.

lms/templates/signup_modal.html

@@ -26,7 +26,7 @@
           <input name="password" type="password" placeholder="****">
           <label data-field="username">Public Username*</label>
           <input name="username" type="text" placeholder="Shown on forms">
-          <label data-field="name">Full Name</label>
+          <label data-field="name">Full Name*</label>
           <input name="name" type="text" placeholder="For your certificate">
 	  % else:
 	  <p><i>Welcome</i> ${extauth_email}</p><br/>