Freeradius can be straightforward or difficult, depending on what you do to set it up. The same goes for Linux and VMWARE This is probably not the forum to get detailed advice on how to setup Freeradius, Linux and VMWARE from scratch. The link that Pradeep sent is probably the best resource you have for freeradius setup.
What does the customer have to authenticate users currently, and why is Freeradius needed specifically? If ths customer has VMWARE and has Windows Server, cannot IAS or NPS be used?