Got the same problem yesterday. Even managed to downgrade to 7.3 and then again report that it is not supported. Stopped at php7.2. Alas, there is another problem at the end of installation (already reported by someone - https://central.owncloud.org/t/sqlstate-hy000-2054/26180/3)
How to downgrade - check this link: [https://www.mysterydata.com/how-to-upgrade-php-7-0-to-php-7-1-or-php-7-2-on-ubuntu-vestacp/]