L1 and L2 rounds will be technical and L3 round will be managerial. Most of the questions will be based on your resumes, so ensure whatever is mentioned in your resume you can answer that.
Don't waste too much time on this company's interview process; you should be able to pass the all the rounds without much difficulty. Afterward, HR will request all necessary documents, but after a few follow-ups, they will inform you that the position is on hold.