Try taking off using DJI Fly to see if it provides the reason for not taking off. As Yordie said, you might be in an authorization zone. If that is the case, you will need to unlock using DJI Fly, then fly using Litchi.
Could it be that DJI Fly is still running in the background? I know that will cause problems if its still running when Litchi is used to control your flight.
I have both applications on one mobile phone, it always asks which one I want to use.
Does it also use authorization zones?
In the summer, I will go to the military training area for an exam. You can go there on the weekend when there is no training, there is a beautiful landscape. Last year, the DJI drone did not take off from the DJI app