How to store and recover emails from macbook to Passport Ultra

I have folders in Mail but when I choose “export” and send them to Passport Ultra the emails don’t show up there.
What appears are three choices:
table of contents
and when I open any of those, there is just “computer language” and no emails at all.
No doubt it’s a simple fix and thank you if you can help.

Hello, I am not a apple user, I wouldn’t be able to help, lets see if another user is able to provide some information.

Thanks Lluna - I’ll stand by and hope to hear from an Apple user!