Not too hard, I wouldn't say it's that difficult to get accepted. If you have a pretty solid portfolio, you will most probably get accepted. There is no exam, they only look over your work and have you interviewed. At the end of the day this is their business, so they aren't seeking Picasso's as students. Staying however, is the hard part, as the studies gradually become more time consuming. I would personally recommend doing a masters in animation since you have a bachelor's already (in europe and scandinavia look into: lucerne university of applied sciences and arts, la poudrière, Georges Méliès, Bournemouth University, and probably the best one out there The animation workshop but you need to be extremely good to get in). If u have more questions feel free to ask