@Calabras -

Export as PDF or Screenshot does not help, it only selects a small area, and I need the whole document offline

The board export feature only exports content that is in Frame, and you must have at least one Frame. For example, if you have a board with 100 sticky notes, and had one Frame with one of those sticky notes in the frame, when you export the board as a PDF, you would end up with a one-page PDF with one sticky note in it.

• More on Frames and and exporting them here:
  https://help.miro.com/hc/en-us/articles/360018261813-Frames#Exporting_boards
• More on exporting boards here:
  https://help.miro.com/hc/en-us/articles/360017572754-How-to-export-your-board
  (the article also notes that the mobile and tablet have limited functionality when it comes to exporting boards:

Miro does not load this board from my iPad and iPhone, why?

I seet you posted another question about this - I will respond in that post:

https://community.miro.com/ask-the-community-45/why-doesn-t-miro-download-my-whiteboard-on-my-mobile-phone-but-everything-beautiful-works-on-my-computer-10376