This seems to be an issue where, for the past week or so, when in a “free trial tier”, the rate limit intention of 1 image per minute (you also see in the error) is immediately been seen as “no images left per minute” by the limit algorithm. It is also discussed elsewhere on the forum with more OpenAI staff exposure to the issue.
The workaround is to feed the API account a minimum prepay credit payment of $5 to boost the DALL-E 3 rate per minute up to 5 by attaining “Tier 1”.