Firstly, you need to check if you are eligible for the dividends. To be eligible for the dividends you need to have purchased the stocks before the ex-date (you will be eligible for dividends if you have sold the stocks on ex-date as well).
You can find the details of the ex-date and record date on the NSE/BSE website.
Should you have purchased the stocks on or after the ex-date, you will not be eligible for the dividend.
If you are eligible for dividends, you will receive the dividends in your bank account (primary bank account linked with Upstox Demat), on the dividend payment date. Even If you have sold shares from your holdings on the ex-date, the dividend will be credited to your Bank account. Suppose you have not received it even after the dividend payment date, you will need to contact the companies' registrar.
The dividend payment date is generally 30-45 days after the record date.
You can find the details of the company registrar on the NSE website under the ‘company information' tab and the BSE website under the ‘corp Actions’ tab.