Ive been trying to install sample data for the theme and i meet all of the requirements shown .. still when i click install sample data it shows a loading icon and nothing happens for hours ..

i finally checked the console and show this message :
load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,plupload&ver=4.5.2:4 POST http://www.joannewong.co.uk/wp-admin/admin-ajax.php 500 (Internal Server Error)

could you please get back to me asap, with regards to what this error is ?
and why im getting it. its freaking taken me hours just to set up a simple sample data