Signal level of DP0601, UART interface

Hi, what level of signals going out/coming in from/out of the UART of DP0601 (ZED-F9P) modul? I have found in the manual: "All the PIOs are supplied by VCC, therefore all the voltage levels of the PIO pins are related to Vdd supply voltage. Does it mean: logic 0 ~ 0V, logic 1 ~ 3V? The datasheet of the ZED-F9P says: “It is important to isolate interface pins when VCC is removed. They can be allowed to float or
they can be connected to a high impedance.” and there is a recommandation to use the 74LVC3G07 driver supplied from modul VCC. Is this driver built-in into the DP0601 unit, or I have to build it by connecting the DP0601 to an other device? Thanks.