I got the same problem on the activation but my case went even worst, now i can’t login in to the admin dashboard. Every time i try i get this msg.
Fatal error: Call to undefined method WeDevs_Settings_API::getInstance() in /home/cjmos/public_html/wp-content/plugins/wp-user-frontend/admin/settings.php on line 13
Someone please help me i want to get my webside running ??