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).
Restart XAMPP.
sudo /opt/lampp/lampp restart
Config database at file: /opt/lampp/htdocs/bwapp/admin/settings.php
Go to address: http://localhost/bwapp/install.php
Link login: http://localhost/bwapp/login.php
Default account: bee / bug