Fraud!! Fraud!!
First of this company offer you job on your expected salary. After that you resign your current company they ask you to share resignation latter.
Then next 4-5 day they will call you for join before the joining date if you say no then they create a story. you are not able join on this date, we have to cancel this employment offer because this is urgently hiring.
I'd not recommend to join this company. Although It is a payroll position so after joining, you will be fired at any time.