I ve got CRL 23379& OBC 5436 in jee adv am I elligible to register for IIST through it??

You can always register for the IIST admission if you satisfy the eligibility criteria.
Refer this link for the minimum marks required and check whether you satisfy that or not.
IIST details


Also, it has past years closing and opening ranks. You can check that as per your category rank it's tough to get admission in iist.
You can try some other college too.

All the best!