Orders placed through Backbar are sent via email. You can choose the contact and email address that the order gets sent to on the Manage Vendors page.
If you are in a jurisdiction where you are required to purchase through a government store or distribution center, if you can send your orders to them via email then you can likely use Backbar for placing your orders. If you are required to provide item numbers or SKUs for your order, you can enter those in for each item and when you place your order those SKUs will be included in the purchase order.
If you are unsure if you can place your orders via email, contact the store or center to ask. In many cases you can place them via email even if it is not advertised on their website. In some states private suppliers can also place orders on your behalf. In those cases, you can email your order through Backbar to the supplier who can then place the order with the state.