The Zero/SAMD21 USB port supports USB host mode using a USB OTG to host adaptor/cable but there is minimal software support. Examples for USB keyboard, mouse, and ADK are included but there are no examples or libraries for USB serial devices.
It might be possible to port USB serial code from the USB Host Library 2.0 but quite a bit of knowledge about USB protocols is required. This library is not designed to work on the Zero USB hardware so some changes are required to use the drivers.