Adobe Flash Player Installation Query

Hi. I keep receiving a message on rebooting my computer that Adobe wants to
install a new version of its flash player. Unfortunately, it doesn't appear
consistently or else I would have had someone sighted look at the screen.
 
the first appearance shows a clear "Install" button, which I click on.
However, the next screen shows two buttons, one with no label and the other
with the unhelpful label of "Q."
 
Can someone tell me what these two buttons represent?

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