Android, do average app need ndk and where are the built files?

The end goal is to figure out why our apps are crashing with libc.so

The following is from firebase crashlytics and we can't say what is causing the crash.

So I dig the crashlytics documentation but it seems we need to tell them where the object files (maybe they contain the symbols?) are

eg)

 strippedNativeLibsDir "$buildDir/ndklibs/obj"
 unstrippedNativeLibsDir "$buildDir/ndklibs/libs"

The paths set above namely $buildDir/ndklibs/obj doesn't exist in my system and I need to find the correct path..

What is my situation here? Below is What I think where I am.. but I'm not even sure..

Our app (and any android app?) uses ndk (because maybe some libraries we use need ndk? we surely don't use native c/c++ code to build something)

But we don't know know where the required ndk obj files are.

To find that out, we need to go through ndk setup process and figure out where they place obj files are?