Hello Manivel,
Please confirm the exact build version of the vCSA (e.g. 6.7 U1 vCSA is: 10244745) and the hosts in the cluster (check them all not just one) - potentially fsOverhead pre-allocated more in previous builds and/or it is just going to take a relatively large chunk initially.
Sorry but it says you will need 7.62TB without dedupe (2.64TB used + 4.98TB savings) so either you have something misconfigured and it is reporting incorrectly or you actually have multiple TB data used here - this might not be VMs, things like ISOs count too - please check this correctly via the methods I said above.
Looks like you are still looking at that from the page with less information, read what I said in the above content and the link.
"I have created a storage policy without "Number of disks stripes per object". Please suggest whether i need to include this or not ?"
Whether you want to stripe sub-components more than the default (SW=1) or not is your choice as administrator of the environment, striping will increase the number of (sub-)components but potentially increase the throughput.
Bob