Not enough credits
The button says what the render needs and what you have; here is what to do about the gap.
Pick a cheaper version: the line under the composer lists what your balance covers — one take, the shortest clip on this engine, an image instead.
Top up with a pack or take a plan from Billing; credits land immediately and the button updates.
In a team, check whether an admin set you a monthly ceiling: the refusal says so, and the Members tab shows it.
A 402 from the API means the same thing; nothing was charged.
Still stuck?
Tell us what happened and we answer within a business day.