In general when an XtremIO is being newly initialized it will be stood up at current target code level. In fact for the X2 models the storage controllers ship from the factory with the latest target code on them to streamline initialization.
Without knowing the name of the download you were looking at, I am going to make some assumptions (which I will explain why I am making).
I assume what you were looking at was the ova download for the Virtual XMS. This would have been labeled as "XtremIO Virtual XMS (vXMS) OVA 6.0.0 for VMware vSphere" on the support site. I make this assumption as the actual software packages are not customer accessible. Support is required to run the install of the software and as such the download is limited to support personnel.
Now to give some further insight into the ova package. The 6.0.0 label is just to signify that this ova is meant to support XMS versions in the 6.x code level. Once the ova is deployed, Dell/EMC support will assist to configure the vXMS with base ip connectivity, transfer the requested software to the virtual XMS and install the software. Again the ova is just providing the base starting point for the vXMS.
For further insights you may also review the following knowledge base article which covers redeploying a virtual XMS.