It depends on the operator! Some providers allow you to board directly using the Bookaway voucher or e-ticket, while others require you to print the voucher or exchange it for a physical ticket before boarding.
To be sure, please always check the instructions in your Bookaway confirmation email you receive when your booking has been confirmed, as some operators include them. This will help you avoid any hassles during your trip. If a ticket is attached to the confirmation email, that's usually what you'll need to present when boarding. If printing or exchanging a physical ticket is necessary, the voucher will provide clear instructions on how to do that.