I got mine recently, straightforward process which took a while because of the lockdowns.
Went to the campus on college Street, paid the fees (around rs 3900) submitted a transcript request form along with a copy of the registration certificate (mandatory)
They ask you to come back after a month which in my case stretched to more than five months thanks to the lockdown. When you go back they have your transcript prepared along with the registrar's sign and seal which could then be couriered directly by CU via speed post (included in the fee)
A representative can do this in case the applicant is not available at Kolkata. But a copy of the registration certificate is mandatory.