Password plugin on virtualmin nginx and RoundCube 1.2.3 version


Im trying to enable password plugin for Round Cube. my server is running On Centos7 and webmin/vrtulamin, instead of Apache we use Nginx for web server and we run PHP 7.0 . We are trying to use RoundCube 1.2.3 version and enable password plugin but nomather what i do i cant seem to set it running.
All the time we get the following error: New password could not be saved.

Any suggestion or working step by step instruction ?