With ducted fans the Lilium design needs 2x the power compared to an Helikopter to hover.
https://lilium.com/newsroom-detail/t...Njc0My4wLjAuMA..
Even so they claim that this stage is short (<60 seconds) certification requirement will be, that under single fault condition the craft still can hover. So the enormous power for hover need to be supplied by an almost empty partial (divided into redundant sections) battery.
To my knowledge all electric aircrafts wait for the wonder battery with several multiples of the current cell capabilities.
From all battery electrification projects flight is the hardest. If you add safety concerns for passenger transport only very narrow use cases are currently left.