For what it's worth, I am running Windows 10 & Acrobat Pro DC Pro - and copying text functions as expected on your sample document. A thought, though, is that the file opened for me (after clicking the link) in a browser, and my browser settings instruct an online PDF to be displayed in Adobe's browser plugin. When opened in the desktop Acrobat application, it also behaved 'properly'. Are you trying to copy the text from inside a browser presentation of the PDF?
Any additional details you can provide might help isolate the issue. (And I understand that I am not using Reader, but Acrobat - trying to reproduce your issue with the tools at hand.
My best,
Dave
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