When I am putting Client ID from Zerodha to Kfintech then it all the time says wrong client id

I am going into this link: Tax Exemption Forms Registration

And trying to add CDSL client ID which is the last 8 digit of the demat account number it shows not valid all the time in the kfintech website…

Can anyone help me with this?

Not explained directly but CDSL Client ID here means the full 16 Digit Demat ID (link for getting it via Console). Please try entering that and it would allow you to proceed forward.

Found a help page in a different section of the website which briefly defines the meaning of CDSL Client ID in their context.