You must either go through the Ibotta App, select New Balance and press Shop. Or, you can use the Chrome (and Firefox) Extension on a PC, sign in and activate it before placing your order.
Please read the details in Ibotta before shopping. There are some exclusions.
I think new balance was one of the excursions-couldn't do it-they send me a $10 gift discount for my birthday this month so I used it-paid for the tax. great