Formcreator protects the directory in the public url

Hello everyone,

How can I limit the right of access to the url address if I want to send a questionnaire to people who I do not want to have access rights in GLPI.
For example, I send this url:10.10.12.57/glpi/plugins/formcreator/front/formdisplay.php?id=2" 
to fill out the questionnaire but if they delete one part in the url they can access the folders and see all USERS in GLPI.
I created a questionnaire in formcreator and I want to send it only to those who do not have access as a GLPI user
How can I protect GLPI?


Thanks in advance.