Why cannot I choose MySQL as database type in the installation page?
Create a info.php file and upload it to your server :


 php_info()



upload the file to your server is docroot then visit the URL http://youdomain.com/info.php
search for pdo_mysql and it should be enabled if it does not exist  contact the server admin and tell him to enable the pdo_mysql (https://serverfault.com/questions/471282/how-enable-pdo-mysql) :




  in your case I think you have just the pgsql and SQLite PDO enabled