Add a DNS entry for cloud.xyz.com in your DNS manager. I will choose Cloudflare.
Then, login to the i-mscp panel, create a domain alias, say cloud.xyz.com

Install owncloud:

echo 'deb http://download.opensuse.org/repositories/isv:/ownCloud:/community/Debian_8.0/ /' >> /etc/apt/sources.list.d/owncloud.list
wget http://download.opensuse.org/repositories/isv:ownCloud:community/Debian_8.0/Release.key
apt-key add - < Release.key
apt-get update
apt-get install owncloud

It will get installed to /var/www/ownlcoud
We will have to move the files to the directory of the new domain alias:

cd /var/www/
cp -a owncloud/* virtual/xyz.com/cloud/htdocs/
cp -a owncloud/.* virtual/xyz.com/cloud/htdocs/
rm -rf owncloud

Set permissions (Check the username for your directory virtual/xyz.com/cloud/htdocs first):

chown -R vu2004.vu2004 virtual/xyz.com/cloud/htdocs/*

Install owncloud by visiting http://cloud.xyz.com, and creating a new admin user and password.
Now that owncloud is confirmed to work, we will add SSL support.
In i-mscp, enable SSL support by visiting Admin settings.
Now, use the “Add/Edit SSL Certificate” to generate a new SSL certificate.

Enable Cloudflare for the domain.
Now you will be able to login to https://cloud.xyz.com