purchased topo maps

You cannot load purchased Garmin maps onto the legacy iR devices (such as the Explorer+). These devices still use the old DeLorme maps (because the devices were developed before Garmin bought DeLorme). The ONLY maps that are available for these devices are those which can be downloaded from the Map tab on your account at explore.garmin.com.

I no longer have an active legacy device, so I am unable to tell you what maps are available. But it will be clear once you look on the Map tab.