@tanalepy
please re-edit your post with the code
so the code is shown as a code-section
See the tutorial-link at the bottom
The code is not called "skript" the code is called a sketch.
No. There might be a possability which would be very dirty ugly programming.
This is the reason why I do not show it to you.
It is done differently.
Your code must be restructured to become non-blocking.
The non-blocking code will run the one and only function loop() in a way that it will work.
This means as long as your DF-player starts standalone there is no possability to sync the code to the sound over time.
You can have it in sync for a few repeatings by carefully tweaking the wait-time. But as longer as you repeat the more deviation between sound and light-effects will occur.
post a picture and the datasheet of the DFPlayer this sounds as it should be very easy to let the arduino send the start-signal
showing code as a code-section
non-blocking timing
best regards Stefan