Hi @Nicdip,
To keep your questions on-topic, have a look at this post:
bert.test implemented the real time clock by using pins A13-A15. Since you already used them for your RGB LED, you will need to use other pins. The Arduino mega has a lot of pins unused under the sensor shield, you can use those and carefully bend the connectors under the shield.
Be advised, you will need to alter the Earthlisteners firmware to include the real time clock.
Kind regards,
VEL342