Usually, whenever an employee resigns, the company withholds the employee's salary during the notice period and pays it during the Full and Final settlement. This is done to ensure that the concerned employee has no dues payable to the company and that the employee is properly handing over their responsibilities before official relieving.
It seems you have a 2-month notice period. Therefore, you have not received your salary for October 2020. I suggest you have a friendly dialogue with your HR about the salary withholding and also to understand the exit policy.
Aim to have a graceful exit. All the best!