Have you checked the Settings? I don't know about Moto E4, but on some phones you have to specifically turn on OTG in the settings, and the default is OFF. Oppos are like that. But on the other hand my Huawei, OTG is always available, and just have to plug in a FAT32 USB drive and it's available immediately. I have a couple of double ended USB drives, one end is type-C and other end is regular USB. So no other OTG adapters needed.
Would Verizon have disabled OTG on their variant of the Moto E4?