While applying for rights shares, it shows 'Please enter your correct DP ID or client ID'?

You need to make sure you enter your 16 digit client ID while applying for rights shares.

Client ID is a combination of your DP ID followed by your Demat Account No.

Your DP ID is IN300214. It is the identification number of the Depository participant (DP), i.e. the entity where your demat account is maintained. The membership of Kotak Securities Limited at NSDL is indicated using this DP ID which will be the same for all Kotak Securities customers.

The Demat Account Number is an 8 digit number used to identify your unique demat account held with the depository (NSDL), through your Depository Participant (DP).