You can apply using the same process as general IPO applications. After clicking on Apply, select your investor type as either Existing shareholder or Employee.
You must hold the prerequisite number of shares in your demat account before applying. You can apply even if you do not hold your existing shares in a Zerodha account, as the Registrar and Transfer Agents (RTA) validates your application using your PAN card.
The RTA verifies whether you held at least one share of the parent company on the day the company filed the Red Herring Prospectus (RHP). Each RHP has specific eligibility criteria that you must meet.