Use PHP 5.x, not use PHP 7.x, because some function of BWAPP can't run.
chmod +x xampp-linux-x64-5.6.36-0-installer.run
sudo ./xampp-linux-x64-5.6.36-0-installer.run
After download BWAPP, extract and copy add dir to /opt/lampp/htdocs/
(dir install XAMPP).