I also ran into this problem.

The solution is to download files from the website: https://github.com/DucLQ92/ffmpeg-kit-audio/tree/main/com/arthenica/ffmpeg-kit-audio/6.0-2

Next, place the aar file in the app/libs folder

Add it to build.gradle:

dependencies {
     implementation(files("libs/ffmpeg-kit-audio-6.0-2.aar"))
} 

Assemble the project