Dear Sujith, if you are holding a category certificate then you will get two ranks from JOSAA. One will be your All India Rank which will be given based on your JEE score and the other rank will be your category rank which is the rank you hold among all the students in your category. This category rank  of yours, will be used to allocate seats in different colleges under JOSAA.

For more details related to JOSAA counselling you can check the given below link -

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/articles/josaa-rank-list/amp&ved=2ahUKEwjPyMS95s_iAhUq4XMBHSnoDtMQFjAAegQIARAB&usg=AOvVaw1NCqK3xz5TRp6kBTcxdgdb&ampcf=1

All the best.
Feel free to ask for any query.

Well it all depends on how you fill the choice list. If the college which you have chosen is available to you for your general rank then your crl is used. Otherwise your category rank is used.
But to be really honest, if you are getting a college from crl then certainly you will get a better college from your category rank. So your category rank is used for counselling and admission.