What port do I plug in the HyperDrive for iMac to?

For iMacs that have two Thunderbolt ports only, you can use any. For the iMacs with two Thunderbolt and two USB-C, the 5-port can plug into either, the 6-port with HDMI will need to plug into a Thunderbolt port, as the non-Thunderbolt ports do not support video.