Just like an OTT platform subscription, a Stock SIP is a weekly or monthly subscription to a stock of your choice. So, for it to go through successfully, you need to ensure you have sufficient funds in your Upstox account on the date of the Stock SIP.
If you have set a Stock SIP by amount, always maintain X% more than the defined Stock SIP amount.
And if you have set a Stock SIP by quantity, ensure you check the price required for the order to be executed at the time of execution and add funds accordingly. 

If you already have an autoSIP, the amount will get an auto debit from your bank account on the due date.