Hi ​@Anastasiya Koshkina, Thanks for reaching out. I hope it's okay to reply in English.

I understand you're trying to edit a file, but you don’t see the Design tab. In that case, it looks like you might only have view access to the file. Could you please check the following?

1. Click the Share] button in the top right corner to open the "Share this file" modal.
2. In the modal, check the “Who has access” section to see what permissions you have.
 

If you’d like to have editing permissions, please follow the instructions in this document: Request to edit a file

I hope this helps! If I missed anything, please let us know.

Thanks again for reaching out.