I commented out this line in single-campaign.php file at line number 60 –
add_filter('give_donate_form', 'mo_donate_form_filter');
and the donation form appears now with an extra progress bar from Give plugin.
In order to debug further I would need to see the error log from the server. May be the libxml that is required by the above filter is not loaded in the server or may be it is something else.
BTW, the above filter is not really critical and the same effect can be achieved via CSS by including this below custom CSS in theme options –
.single-campaign .entry-content .donation-form .give-form-title { display: none; }
.single-campaign .entry-content .donation-form .goal-progress { display: none; }
If there are no other issues, you should be able to get along with the above CSS.
I entered the above custom CSS for now in your installation until I see the actual error message.