As for this integration, there are a few easy steps which you'll need to follow.
Navigate to your backend
Joomla > Extensions > Plugins Manager and then search for Content - Komento plugin. Please ensure this plugin is turned on.
Next, navigate to Komento's integration configuration page.
Joomla > Components > Komento > Integrations. Select VirtueMart in the component list
Under the Workflow tab, make sure that Enable Comments is set Yes and set the categories assignment appropriately.
Next, navigate to VirtueMart Configuration page,
Joomla > Components > VirtueMart > Configuration > Shop Settings. On this page, find Enable Joomla Plugin and make sure it is ticked. Finally, click on Save button to store this configuration.
That's all and you're ready to go!