Hi all 
While we haven’t been able to duplicate this at the moment so far we feel this may be permission related, if anyone continues to see that prompt beyond the wp-config.php edit (perhaps @nametags4u ) may we please have you try running the following command?
docker exec devkinsta_fpm chown -R www-data:www-data /www/kinsta/public/
If the issue persists beyond that may we have the output of the following:
On DevKinsta (Docker):
docker exec devkinsta_fpm ls -al /www/kinsta/public/
docker exec devkinsta_fpm ls -al /www/kinsta/public/SITE_NAME/
On Windows (Command Prompt):
icacls C:\Users\USER\DevKinsta\public
icacls C:\Users\USER\DevKinsta\SITE_NAME
Thank you! Hopefully this helps pinpoint what might being on there for anyone still having difficulties!