why play not plays ?

[Jouet]

It is required that the government play an important role in stopping depressions and recessions in industrialized countries.

Why don't we use plays instead of play in the above sentence?

Source : Ultimate grammar workbook published in Thailand

[Joe]

ah ha. You’ve run into the dreaded subjunctive:

https://www.englishclub.com/grammar/subjunctive.htm

That’s why it says “play” and not plays.

The policeman ordered that he stop.
The president insisted that he be present.