OpenWRT is not the same as Windows/iOS and does not install drivers/software automatically. OpenWRT has limited availability of drivers for LTE USB modems, depending on the modem chipset. You can try to look up the modem chipset of your Novatel Wireless Ovation MC547 and check if there is a driver that can be installed.
I recommend that users to confirm compatibility before buying USB modems, which are generally used in WIndows/iOS computers. GL.iNet has a list of tested modems somewhere on their website.
I do not work for and I do not have formal association with GL.iNet