Hello Aqib Azad.
As per the Supreme Court's order of no age bar in 2017, the same is applicable for admission in Calcutta University for pursuing the five year integrated Law course of BA LLB. Hence you seem to be eligible for the same. You can apply for admission in the said course even if you are 23 years of age as there is no maximum age limit. Make sure that you fulfil all the other specified ELIGIBILITY CRITERIA. You can use the link below for any other details regarding the same.

https://www.google.com/amp/s/law.careers360.com/articles/calcutta-university-ba-llb-eligibility-criteria/amp
Best of luck