Sentry Policies create mappings between group policies for Meraki networking equipment and tags in Systems Manager. This allows for a form of dynamic policy configuration, akin to Cisco Identity Services Engine, without the need for a dedicated box in your network. Group policy settings like traffic shaping, scheduling, security and VLAN rules can apply to devices based on any of their tags in Systems Manager. By adding dynamic tags, such as security policies, devices can automatically move between group policies based on the posture of the device.
To set up a Sentry Policy, navigate to Network-wide > Configure > Sentry Policies. Select the Systems Manager network in question followed by a scope, the tags for the devices enrolled in SM, and finally the group policy to apply to devices in that scope. See the group policy documentation for more information on the network-side setup.