A final ㄱ (batchim) sounds like [ㅇ] when the next syllable starts with ㄴ or ㅁ.
You can read words like 한국말, 작년 and 박물관 aloud, saying ㄱ as [ㅇ] before ㄴ and ㅁ.
Downloads are for signed-in learners — it takes a minute and it is free.
That download may have been removed, or the link is wrong.