The kit is powered through the USB port and contains two LDO regulators, one to generate 3.3V for the on-board debugger, and an adjustable LDO regulator for the target microcontroller PIC16F15376 and its peripherals. The voltage from the USB connector can vary between 4.4V to 5.25V (according to the USB specification) and will limit the maximum voltage to the target. The figure below shows the entire power supply system on PIC16F15376 Curiosity Nano.
Figure 1. Power Supply Block Diagram