MAX14578 LDO connection not in use
That's the same configuration as on the first "Typical Application Circuit" on page 9 of the datasheet.  Leave \$L_{OUT}\$ unconnected and connect \$V_B\$ to \$V_{BUS}\$ of the USB connector and via a 1\$\mu F\$ capacitor to ground.

If you're using the version with \$L_{OUT}\_SNS\$, connect it to \$L_{OUT}\$ and let them float together.