CWP: How to Install new Theme (Roundcube Plus free skins ) for Roundcube

Visit the following website https://roundcubeplus.com/portfolio for Roundcube Theme and select 'Skin - Litecube Free' and Follow the next procedure to download.
After  successfully registration, You will get the License key and download link .

$config['license_key'] = 'RCP-wZpzy---xrq8';

In order to use the skins or plugins, you must add your license key to the Roundcube config file. Edit the file config/config.inc.php and place this line at the end:

# vi /usr/local/cwpsrv/var/services/roundcube/config/config.inc.php
$config['license_key'] = 'RCP-wZpzy---xrq8';

Roundcube Plus free skins add a new look to the Roundcube program. They are simplified versions of their commercial counterparts: they don't include the mobile support.

Installation steps

1. Upload the tar.gz file to /usr/local/src directory

2. Copy the directories 'skins' and 'plugins' to the directory where your Roundcube is installed.

# cd /usr/local/src/
# tar xvzf roundcube_plus_skin_litecube-f.tar.gz 
# cp -rvf plugins/* /usr/local/cwpsrv/var/services/roundcube/plugins/
# cp -rvf skins/* /usr/local/cwpsrv/var/services/roundcube/skins/

# chown -R cwpsvc:cwpsvc /usr/local/cwpsrv/var/services/roundcube/plugins/
# chown -R cwpsvc:cwpsvc /usr/local/cwpsrv/var/services/roundcube/skins/

IMPORTANT: If you already have a full version of any Roundcube Plus skins, do not overwrite the xskin plugin as it will cause errors when using your existing skins.
3. Edit the file 'config/config.inc.php', find the line that begins with $config['plugins'] and add 'xskin' to the array, like this:

# vi /usr/local/cwpsrv/var/services/roundcube/config/config.inc.php

// List of active plugins (in plugins/ directory)
$config['plugins'] = array(
    'additional_message_headers',
    'archive',
    'emoticons',
    'help',
    'hide_blockquote',
    'identity_select',
    'legacy_browser',
    'managesieve',
    'markasjunk',
    'newmail_notifier',
    'new_user_dialog',
    'new_user_identity',
    'password',
    'rcguard',
    'show_additional_headers',
    'subscriptions_option',
    'userinfo',
    'vcard_attachments',
    'zipdownload',
    'xskin',
); 

If the $config['plugins'] line doesn't exist in your config file, add it at the end of the file.

4. If you'd like to use litecube-f on the Roundcube login screen and as the default skin for the newly created user accounts, edit 'config/config.inc.php', find the setting $config['skin'] and set it to litecube-f'. If this setting doesn't exist, add it at the end of the file, like this:

# cd /usr/local/cwpsrv/var/services/roundcube/config

# vi config.inc.php 
$config['skin'] = 'litecube-f';

5. If you'd like to use your own branding images or customize other skin settings, copy the file
plugins/xskin/config.inc.php.dist to config.inc.php and follow the instructions given in that file.

# cd /usr/local/cwpsrv/var/services/roundcube/plugins/
# cp -p xskin/config.inc.php.dist xskin/config.inc.php 

License Usage

Each purchased item can be used on a single Roundcube installation. If you want to use the software on more installations, you must get more licenses by purchasing additional copies of the software.

If you use the software on more installations than you are permitted, you will be in breach of the license agreement terms and your downloads will be disabled

The Roundcube Plus free skins are covered by a commercial license agreement (see the file LICENSE for details).

Copyright and credits
---------------------
Copyright (c) 2011-2018, Tecorama LLC (http://roundcubeplus.com)

This post is based on this article.
How do I install the skins?