I can not export OSM data because I do not see the “Download Data” tab that appears above the coordinate frame.
Can someone help me that can be done to review this tab?

I wouldn’t expect to see a “download data” tab anywhere, but I would expect to see an “export” button. Maybe that’s just a language difference - I see “export” in English, but the words in your language translate back to “download data”. What do you see? Could you post a screenshot somewhere and link to that?

One other thought - whether what you get from that would be useful depends on what you want to do with the exported data, so it might be worth mentioning what you are actually trying to do.