it seems the libraries generated by ./ndk-make.sh are not there or cannot be found.
i would first check, after executing ./ndk-make.sh (not: ndk-build) manually from the command line, that the files
./jni/armeabi-v7a/libdeltachat.a
./jni/x86/libdeltachat.a
./jni/arm64-v8a/libdeltachat.a
./jni/x86_64/libdeltachat.a
exist and have several megabytes as file size. Android Studio is not needed at this point at all.