How can an NRI apply for an IPO?
The process for applying for an IPO is the same for an NRI and a resident individual. You can apply for an IPO through Zerodha using your UPI app (if your bank supports it for NRE/NRO accounts). Click here for the steps to apply.
If your bank does not support using UPI with your bank account, you can apply for IPOs through the netbanking ASBA facility provided by your bank.
Read this post on TradingQ&A explaining the process of applying for an IPO using netbanking.