Now you have to wait

During the following months, if you're lucky, you will not do anything, just wait. As I said, if you're lucky.

If not, you can get emails from the host university, telling that some of the subjects you have requested could not do them (as happened to me. )

In principle it is quite normal andther is any problem, you have to convince them that you are sufficiently prepared to take the subject (and you'll read a book, for example). If not, then you will change the subject (or subjects) for different ones.

So it is nice to have a reserve subjects. Until June, the only thing that you have to do is wait and talk to the host university or some of their teachers, to see how they manage the validation. Good luck!