DFPLAYER mini MP3 player questions..... how to mount/use?

My question is about the DF player “mini SKU DFR0299”:

https://wiki.dfrobot.com/DFPlayer_Mini_SKU_DFR0299

Basically what I'm wanting to do is mount a micro SD or SD slot in an electronic toy device that runs on 4.5 volts.
When you normally flip the switch and turn this thing on, it plays its own preprogrammed music/sounds.

I want to cut the wires going to the speakers, and instead run them to this SD player.   Then hook the SD player up to the 4.5 volt power source and speakers.
That way when you turn the toy on, instead of playing the sounds it normally does, it will play whatever MP3 file is on the SD card.
Does this make sense?   Give it a customizable soundtrack.

I believe this will do the job, but I'm somewhat new to this and am not sure by the explanation of the product if this will do it alone, or if it would require a separate Arduino, or a breadboard…. and how would it be mounted so that it would be basically a slot to insert SD card on the toy.

Can anybody help?    Thanks!