Thank you for reaching out to us on the forum! Our platform uses the NGINX web server which does operate differently from Apache in that it doesn’t utilize .htaccess files to include additional configuration directives. NGINX does require that all configuration changes be made directly into the site’s configuration file.
This type of NGINX configuration adjustment does require that our Support team make the modification. Please do chat in with our Support team via MyKinsta or by sending an email to support@kinsta.com. Our team would be more than happy to help you with configuring password protection on this directory!