We couldn't reproduce your issue yet. Could you think of any peculiarities of your deployment that makes it fail in your case?
Can you also download the
installer.php file in the proper folder and access to it to see if you can pass the wizard manually? Please, also make sure that all the pre-installation checks are good.
In order to download this script, you can execute the following commands on your instance:
sudo curl -Lo /opt/mantis-2.23.0-1/apps/mantis/htdocs/admin/install.php https://raw.githubusercontent.com/mantisbt/mantisbt/release-2.23.0/admin/install.php