Adafruit has a complete tutorial on connecting the RGB matrix.  I connect Dupont Male-Male jumpers directly into the ribbon connector and then connect these into the Arduino processor via the jumpers.   Cut the power connectors and directly connect these - and all the other components that use +5v and GND - directly to the power adapter leads so nothing 'draws' though the Arduino.

The first thing to do is to load up the soundboard.  The files are coded as OGG to reduce size and I edited them with Audacity.  Each chime, cuckoo clock or bell sound is coded and 'fired' when the appropriate pin on the soundboard is pulled low.  I have the files and will either post or send them if you want.  Bells, chimes, cuckoos are coded as intermediate or trailing and assembled by the clock.  Speaker is connected to the Board (make sure you get the one with the amp and speaker (not headphone) outputs.  There's also an "I'm active" pin that tells the clock to wait.   Instructions for loading, building and wiring are on the Adafruit pages too.

Switches are coded as pull-up and connected to appropriate Arduino pins and GND (See connections document -- I haven't learned how to FRITZ yet).

These are I2C connected to power and SDA and SCL

I've included code and connections for LDR control of brightness, but lately I've been omitting these on my clocks and relying instead on time-of-day changes.  Its up to you.

Depending on the enclosure you use you put the components in, ensure everyone that requires +5v and GND is connected and set the clock.