Since you have cleared the cutoff, you can also survive campus life. Knowing you are a slow learner is winning half the better. You can come up with strategies to overcome your limitations. Life at IIMs, XLRI, and IIFT is fast-paced and can be intimidating at first. But with time and effort, you can stay updated with the coursework. No one is good at every subject. Try to find your area of interest, and work on it.
Not every student has the same level of merit or studying capacity. Anyone who is willing to accept the level of difficulty can work towards the development of himself/herself in both academic and non-academic matters.
The points below give a brief overview of the scenario in institutes that you should consider to excel in such institutes.
Therefore, it is possible for a slow learner to sustain in institutes like IIMs, XLRI, IIFT, etc. They just need to work hard in their areas of concern, and not give in to the pressure.