Fatal Error after installing Ultimate Facebook

Hello guys!!
I'm new in Wordpress & Co. and after I installed Ultimate Facebook into my Wordpress website I received this message:
Fatal error: Cannot use object of type Wdfb_OptionsRegistry as array in /home/content/06/11718806/html/wp-content/themes/dano/include/data-install.php on line 10
Now I can't get into my website anymore, how could I solve this issue?
Thank you very much in advance