If you have a case on your phone, make sure the usb-c end will fit into the opening. I have an Defender and the Sandisk Ultra 64GB Dual Drive USB Type-C - SDDDC2-064G-G46 style didn't fit but the Patriot Stellar-C Type-C/USB 3.1 64GB Flash Drive (PIF64GSTRCOTG) style did.
Side note...the Patriot...