PMP Practice: Estimate budgetary needs based on the scope of the project

Tane Whenua-Clarke is managing a mobile app development project for Marble Octopus Group, a startup creating a fitness tracking application. The executive team initially requested a detailed 18-month resource plan with fixed team assignments and monthly budget forecasts. However, after the first planning meeting, Tane learned that the product features are highly experimental, customer preferences are unknown, and the company expects to pivot based on early user feedback every few weeks. The CTO has emphasized that speed to market and learning from users are critical success factors. The finance director still insists on having budget predictability and wants to see a comprehensive resource allocation plan before approving any staffing. What should Tane do to best plan and manage resources for this project?