Blank page after install and login

[Mustard]

I just installed Getsimple in "one click" on my hosting service, After install completed, I logged in and then got a blank page.
I activated debug mode, and got this :

What shoud I do ?
Thanks

Fatal error: Uncaught Error: Call to undefined function get_magic_quotes_gpc() in /home/clients/f4eaab6e24619d6355c413125527cfbb/sites/giuliafraboulet-therapeute.fr/admin/inc/basic.php:689 Stack trace: #0 /home/clients/f4eaab6e24619d6355c413125527cfbb/sites/giuliafraboulet-therapeute.fr/admin/inc/logging.class.php(128): safe_slash_html('admin') #1 /home/clients/f4eaab6e24619d6355c413125527cfbb/sites/giuliafraboulet-therapeute.fr/admin/inc/login_functions.php(64): GS_Logging_Class->add('Username', 'admin') #2 /home/clients/f4eaab6e24619d6355c413125527cfbb/sites/giuliafraboulet-therapeute.fr/admin/inc/common.php(363): include_once('/home/clients/f...') #3 /home/clients/f4eaab6e24619d6355c413125527cfbb/sites/giuliafraboulet-therapeute.fr/admin/index.php(17): include('/home/clients/f...') #4 {main} thrown in /home/clients/f4eaab6e24619d6355c413125527cfbb/sites/giuliafraboulet-therapeute.fr/admin/inc/basic.php on line 689