I have just installed it on 4.3.1 and working. If you have access to wordpress sources go to folder:
wordpress/wp-content/plugins/free-images-pictures/
And open the file to edit:
free-images-pictures.php
Try to replace the 13th line:
include_once("config.php");
by:
include_once(plugin_dir_path( __FILE__ ) . "config.php");
Go to admin panel and try to activate the plugin now.
If not working, please send me what version of PHP you are running the wordpress. Thank you!