After the interview was successful, HR said that he would send me a formal office. Is this express, SMS or email?

It should be an offer, not an office, which means that the formal admission notice is electronic now.

I just changed jobs two months ago. He asked you to print out a few pages and sign them (including employment agreement, salary, vacation, etc. ), and then scan and send it.

There must also be a medical certificate for the things handed over.