Problems installing any version of Nextcloud on ASUSTOR ADM

I am running Nextcloud 15.0.5. installation on Asustor ADM 3.3.1.RIH2. After entering and submitting connection info on installation form it redirects me to a blank index.php page. Instead of “localhost” I entered “” (MariaDB port). Before that I created a blank database “nextcloud” as seen in phpmyadmin. Also, when I try to install Nextcloud 12 from App Central, installation actually populates the previously blank database, but also redirects to blank index.php page.

No matter what connection data I enter into Nextcloud 12 installation form, it always redirects me to a blank browser tab. Nextcloud 12 installation can DID create user in database, so DB connection is working? Why can’t I just proceed with installation?

Do the log show anything of interest? There should be a json-formatted log file in the data directory named nextcloud.log.