Download the latest Foldr.4.x.xVB.OVA and open the VirtualBox console. Click File >> Import Virtual Appliance >> Open Appliance and browse to the OVA file. Review the default settings, these are ideal for most installations and if necessary modify the path where the Virtual Machine files will be stored. Agree to the licence terms by clicking the Accept button.
The OVA is imported and the Foldr virtual machine will be created. Once this process has completed power the VM on by clicking Start.
Mid-way through the initial boot sequence you will have to agree to the EULA to proceed.