If you're operating a paid network and have taken payment in a different way than the usual PayPal/Stripe or wish to allow a user access free of charge follow this guide.
click 'WiFi' icon on the bottom left side of the screen
scroll down to the 'Settings' tab and click 'Payments'
in the top right of the payments screen, click 'Manual Payments'
From here you can add a manual payment to their account, you will need to add an email address to add the payment to their record properly and a WiFi plan. Please note that this will not bill them, Manual payment is used for customers who have already paid for services (for example, paying in cash).
You can also edit the plan defaults, i.e. adding extra time, devices or payment amount.