Hello everyone!

I want to buy a train night ticket from Zuerich to Ljubljana on the 6th of July to book my seat in advance. 
But it’s a paper ticket and the estimated delivery date when I will be able to receive it is after my departure from my country. 
Do you know if there is any option where I can buy it in France in a train station or it’s not possible to buy an international train ticket from France? 
Otherwise, I can probably buy it when I will be in Zuerich but I’m afraid there will not be enough seat available to buy it just one day before the trip? What do you think?

Thanks for your answers