Fatal Error When Installing

[Fri Jan 17 14:34:46.990996 2020] [php7:error] [pid 14038] [client 168.235.186.245:18068] PHP Fatal error: Uncaught Error: Class ‘Rahe\\Simple_Image_Sizes\\Main’ not found in /nas/content/live/sdssoclient/wp-content/plugins/simple-image-sizes/simple_image_sizes.php:42\nStack trace:\n#0 /nas/content/live/sdssoclient/wp-includes/class-wp-hook.php(288): init_sis(”)\n#1 /nas/content/live/sdssoclient/wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters(NULL, Array)\n#2 /nas/content/live/sdssoclient/wp-includes/plugin.php(478): WP_Hook->do_action(Array)\n#3 /nas/content/live/sdssoclient/wp-settings.php(392): do_action(‘plugins_loaded’)\n#4 /nas/content/live/sdssoclient/wp-config.php(119): require_once(‘/nas/content/li…’)\n#5 /nas/content/live/sdssoclient/wp-load.php(37): require_once(‘/nas/content/li…’)\n#6 /nas/content/live/sdssoclient/wp-admin/admin.php(34): require_once(‘/nas/content/li…’)\n#7 {main}\n thrown in /nas/content/live/sdssoclient/wp-content/plugins/simple-image-sizes/simple_image_sizes.php on line 42, referer: https://sdssoclient.wpengine.com/wp-admin/themes.php