What is the purpose of the libc/lib64 folder? Missing libnsl.so

I'm downloading the x86_64 Linux hosted cross compilers from:
developer.arm.com/.../downloads

I had some compiler errors complaining that it couldn't find libnsl.so . When I looked in the toolchain, I could see some nsl files listed:

$ find -iname "*.so*" | grep "nsl"
./aarch64-none-linux-gnu/libc/lib64/libnsl.so.1
./aarch64-none-linux-gnu/libc/lib64/libnsl-2.31.so

I can see a softlink here:
libnsl.so.1 -> libnsl-2.31.so

What are the purpose of the files in?
gcc-arm-10.2-2020.11-x86_64-aarch64-none-linux-gnu/aarch64-none-linux-gnu/libc/lib64

I don't see any header files. I also am not sure why there is a softlink for libnsl.so.1 but no libnsl.so?