Convert .vbk to Pdf

I have five books in .vbk format latest version. However, they are some how encrypted. I am unable to convert them to Pdf. I will share just one book and the freelancer will have to convert that one and on successful conversion, will tell me virtually how to convert the other 4 books or I will send the other 4 books and they can convert them as well. I am attaching one book. So anyone who can convert this book can get the contract.