The labour force of non-disabled, non-student[1], non-over-65 is smaller than 156 million. You have to subtract those people (Of which there are a lot of) from that metric (Instead of just the unemployed metric), to get an apples-to-apples comparison of non-disabled, non-studying, non-senior workers/non-workers, which, alas, the article in question does not.
You'll also find a lot of the remaining employed people to be significantly under-employed, compared to people doing 40+ hours/week.
[1] 40% of undergraduate students, and 76% of graduate students have >30 hours of work/week. [2][3]
[2] https://www.theatlantic.com/politics/archive/2015/10/at-univ...
[3] So, instead of subtracting 20 million from the unemployed bucket, we need to subtract ~10 million from the employed bucket, and ~10 million from the unemployed bucket. Repeat this process for high school students, persons with disabilities (Some of whom do, in fact, work), and seniors, and you will get to something more resembling a 6:4 ratio.