PCA9865 Power supply

Hi, I really don't know much about all of this but I've bought a Sunfounder PCA9865 servo controller board.

I'm trying to connect it to my Arduino Mega but it seems to be unable to draw power from the power source rather than the Arduino. Right now, I'm supplying power using a battery module from Rex Qualis that can give the PCA 9865 5 volts. I'm unable to get the board to work.

I was wondering if I could just attach a power supply directly to the servos but I can't find a battery that can support four servos. I'm using four continuous rotation servos(the make is FS90R). I have no clue how to work for the servo controller board and am having trouble finding a battery that can directly give power to the servos.

Also, I was wondering if I could just connect all the servos to the same power source. I just need help finding one

Study these pages first.