Open the Website, goto the page, select New, create Username/Password using a pre-determined 4 char prefix for username followed by 4 digits of chars. Allow user to print the voucher.
Pretty simple project and will not take an excellent programmer 2 days to do it. There is No API available. The only API to CoovaOM is JSON but there is no reponse info to provide. You maybe working off their Website possibly capturing the website script. A specs will be avaiable to qualified bidders.