While I can only speak English, I ran your question through a translator:
Can you tell me if I can use younity with my windows 7 off but being linked with my smartphone ... Is this possible?
I think you are asking if your computer can be off but still have your files be accessible on your phone.
Unfortunately, no, younity cannot access file on a device that is off. Your computer must be on, connected to the internet, and if it's a laptop, the lid must be open.