Volume of recording?

Hey everyone, I've been recording short loops, just using stack (not separate d1, d2, etc.), to wav and importing the wav to Audacity to normalize. The audio seems fine when I play it back on my computer and phone, but it's really low when I play it in my car (or stereo). Is this is compression issue? Would something like this fix it?

If so, how do I use it? TIA!