It depends. If you only want to get the location from the GNSS, use getLocation() from custom Tracker Edge firmware.
If you want to get the location information using Location Fusion enhanced location (taking into account Wi-Fi geolocation), you need to subscribe to enhanced location events. Note that this means you will need to claim devices (Tracker device are normally left unclaimed, but this mode cannot be used when subscribing to events). Also each enhanced location counts as an additional data operation, in addition to the original loc event from the device.