Plesk

Add Plugin Manager Roundcube on Plesk Server

Check you version of Roundcube

Go to: https://myroundcube.com/myroundcube-plugins/plugin-manager
Download the plugin manager version for your roundcube

Extract and upload the the roundcube plugins directory
extracted

Upload to

# /usr/share/psa-roundcube/plugins

Modify the config file

# /usr/share/psa-roundcube/config/config.inc.php
$config['plugins'] = array('password', 'markasjunk2', 'sieverules');

Change to

 # $config['plugins'] = array('plugin_manager', 'password', 'sieverules');

Access Roundcube and login. Click About

about

This should pop up

file

Add the file to roundcube

# touch /usr/share/psa-roundcube/urv58kf60qjia0n1h447mr8i12.myrc

Go to Settings > You Should now see the Plugins Manager