why can’t register using smartphone?

Hi,
I’m testing this website: http://www.installersrls.it and I’m tryin to create a new account using my smartphone. After I’ve sent my first request to register I receive an email to set a new password and everytime I try to set it systems tells me to set it again. If I test on a pc everything works…
where’s the problem? Please, can you help me?
Thanks