If you have a my.vmware.com account and software licenses for vSphere products, you should be able to login and download it. I don't know 100% if you can download that version of the vCenter Server Appliance without a myvmware account, but you can try. See this link - https://my.vmware.com/group/vmware/details?productId=353&downloadGroup=VC55U3.
If you need it for evaluation, you can only get the latest version of VCSA. You will get the access to previous version only if you own a valid license.
Abhilash B LinkedIn : https://www.linkedin.com/in/abhilashhb/
