The Cash Drawer opens based on commands that are sent through the Molo Receipt Printer. In order to get the Drawer setup, please complete the Setting Up Your Star Micronics mC-Print3 Desktop (Ethernet-Based) Receipt Printer.
Once that is completed, Cash Transactions, Check Transactions, and selecting Actions > Open Drawer from the POS Screen will push the drawer open.
Note: Cash drawer cables are labeled to indicate which end connects to the printer and which to the cash drawer. If inverted, the cash drawer will not operate. Check to make sure the end of the cable labeled "PRINTER" is connected to the printer, and the end labeled "CASH DRAWER" is connected to the cash drawer.