Replace some LEDs with diodes in relay circuit
If you are unable to power the relay module with Raspberry Pi (i.e. the relays do not switch  properly), it is because the module requires 5V input but RPi GPIO can only output 3.3V.

This problem can be solved by powering the relays with external 5V voltage source.

Follow this diagram:



The Low Power message is due to the relays drawing quite a lot of current from RPi power supply. Removing the LEDs won't solve the problem as those LEDs don't consume much current.