How to use LRS engine in Sage?

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I run Sage on my MacOS using terminal. As part of a project I am doing, I need to use the lrs engine:

def getVolume(self,eng='lrs'):
    """
    needs Sage 5.9 for 'lrs' engine
    """
    return self.poly.volume(engine=eng)*factorial(self.poly.dim())

However, this getVolume() function does not seem to work and always returns 0. So, I did some research and I am pretty sure my system does not have the Lrs engine at all. I checked for Lrs using this code: https://doc.sagemath.org/html/en/refe... and it told me that Lrs is not there.

I am quite confused about this since I downloaded Sage very recently (just 1-2 months ago) and it should be there? Am I doing something wrong? If it needs to be installed, how would I go about downloading this library so I can use it?