Roundcube script installation fails "as it requires PHP version 5".

I want to install RoundCube under virtualmin but I got this error:

This script cannot be installed, as it requires PHP version 5.
This script cannot be installed, as this virtual server does not meet its requirements : Could not work out exact PHP version.

However, according to RoundCube site, versions 1.2+ support PHP7 (the version I have on server).
The script on server is 1.2.2. Why virtualmin asks for PHP5 then? What should I check as possible source of this error?

My system is:
Operating system FreeBSD 10.3
Webmin version 1.810
Virtualmin version 5.05