hi, at what step do you get the http error exactly ?
If you are activating the license in all workstations, remember that you are authorized to install each Stand-alone license in one only computer. Reactivations are allowed only by hardware changes or to replace a computer, but not for using a license in several computers.
If you are using them as render nodes, in this case it's not necessary to install the license. The setup program includes a specific option for render nodes, which doesn't require a license.