You will need to install the correct JCE version corresponding to the the JDK version which the client has set for his application. Below are a few examples of the most used JDK/JCE version and links from where to download them:
1. Download the archive jce_policy-$.zip and move it to your home directory (/home/user$) using Cpanel > File Manager.
PS. The symbol '$' stands for dynamic values.
2. Login to your server via SSH.
3. Navigate to the home directory of the user /home/user$/.
# cd /home/user$/
4. Extract jce\local_policy.jar and jce\US_export_policy.jar from the archive to the folder /usr/local/jdk$/jre/lib/security, overwriting the files already present in the directory.
# unzip jce_policy-$.zip
-- generally there will be a sub-folder in this archive, in this case navigate onto it as such
# cd UnlimitedJCEPolicyJDK$
# cp -rf *.jre /usr/local/jdk$/jre/lib/security
5. After that restart the Tomcat enviroment from your Cpanel > Private JVM plugin.