If you own shares on the "record date", you get the full dividend, even if you sell a day or two later. The dividend date is a few days after the record date. But I don't see information for Sept 2019, and the data for June 2019 and June 2018 aren't consistent. So maybe in the second week, maybe the third week of September.
The article has a few big problems with it's comparisons. Once matter goes beyond the event horizon of a black hole, all of it is gone. Germany's 2 year bond yields -0.85% right now, so if you buy $10,000 worth of those bonds, you'll get $9,830 back after 2 years of negative yields. You'll lose -1.7% and not -100% like the articles "black hole" comparison might suggest.
The article also makes a comparison to CDOs, at which point I had to stop reading and skim. CDOs were leveraged to the point that a tiny loss was magnified thousands of times, creating a financial meltdown. Where's the leverage with negative interest rates? If you invest at -0.85%, you lose -0.85%. There's no leverage there. It's a wildly inaccurate comparison.
I think the article is making false comparisons in order to scare people.