You purchased SportMart, and it was meant to be a bundle package. YOU CAN’T INSTALL SportMart into your current Joomla template, because it is already a Joomla Template. You actually need MaterialMart or CleanMart.
OffCanvas Cart is theoretically not possible to include to a Virtuemart Template; the base joomla template must be suitable to integrate the off-canvas cart module; which is really really hard. This is why we don't create standalone canvas cart plugin/module.
I just switched your product from SportMart to MaterialMart and sent you the download link ;)
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