Relic Castle

So one of my friends has a problem with the looping audio. We're using the Fmod extension made by Yuri and Audacity's loop metadata. We followed the script and set our music we want to loop. However, when we start it we got this error here.

"This isn't the RGSS104 library!"

While Yuri did mention you need the RGSS104.dll script to work, we don't know where it is. How to find it and use it to fix the audio problem?