I scheduled the interview in 2-weeks with the CTO and asked him if it is okay but not response from him. the day of the interview he kept waiting just to send me an email after the interview should have started telling he has to reschedule with no more details. After i contacted the job poster (HR) and told her about what happened he reached out again to set up a date. during the interview all the questions were about ML although the job was about backend engineering.