The application tells me « L’application Mail n’est pas configurée ».
This message has not been translated. Sorry English people!
The message means the iPhone embedded Mail application needs to be configured to be able to send mails.
The application generates a file that need to be sent on the remote iPhone, iPad or iPod so as to deploy it. The generated file is send via Mail application. You need to check Mail SMTP settings in the iPhone Setting menu.
My friends receives the mail but he can’t get access to WiFi.
Either you have provided erroneous parameters in the app form or your modem is configured to filter Mac adresses of new devices. Some modem have this security feature enabled by default. Just log in you modem interface (you can try the shortlink button in the app to access it easily but it does not work for all modems), find the Mac filtering option in the WiFi or Wireless settings and disable it.