The cash drawers you have been supplied with from Toast work in tandem with the receipt printer they are attached. There is a telephone cable that runs from the port on the back of the cash box to port in the back of the printer.
Additionally, in the Toast app's Device Settings you can enable and disable whether or not that tablet specifically opens the drawer automatically when a payment is taken using cash. If the device setting is set to NO, the cash drawer would not open.
Let's take a look at Device Settings within the Toast App:
As you can see, the Cash Drawer option (below) is currently set to NO for the device. You can update this to YES by tapping on this option and selecting "Yes" from the next screen.
If this is not the issue, lets move on to the connection and verify that the cable that runs from the cash box to the printer is securely connected on both ends.
If it is not, secure the connection and that should resolve the issue.
If that does not resolve the issue, verify the tablet settings that the tablet is connected to the correct wifi network. It should be connected to the network that to which the printer is connected.