GSuite Routing Options Differing from Documentation

You can download it by retrieving a back up of your email account with Google takeout. Note that you can select which labels you want to download, so no need to download your entire Gmail account. Also, it usually takes a few hours for Google to prepare the archive (depending on the size of your Gmail account).

The back up of your email account is a .mbox, that you can open using Thunderbird + importexporttools addon. Windows MBox Viewer didn't work for me as my 1.4 GB .mbox file seemed to be too large for it (1.4 GB).

I travel a lot, and live 6 months in the EU and 6 months of the year in Asia. I have encountered that message many times, on both recently used and unused accounts. It is usually because I am using a different [borrowed?] PC, iPhone etc. (and, possibly, in conjunction with the fact that I am in different part of the world - although I not 100% sure about that).

I have found that (if I am able to and) I go back to the last machine that I logged onto that account with, then when using the same correct password, I no longer get that message, and I can log on without issue.

Try doing that, if, firstly, you can remember the last machine you accessed the account from, and secondly, are still in possession of said machine.

Hope that helps.