The PCB antenna has 2 elements, and their length (they should be equal whatever the length is) will determine what frequency the dipole resonates at.
The pigtail length determines how much of the signal is reflected back into the transmitter so you should make a bit of an effort to calculate that based on your RF/coax cable type, and its length from the TX output to the antenna center pin (including connectors). There are many calculators online for this.