I'm able to download a users only story entering user/pass on request.
With user/pass and always_login set, it also works fine for me without asking:
Code:
[archiveofourown.org]
always_login:true
username:Name
password:Password
My only thought is that when I last logged into AO3 in browser, it asked for a new user-terms agreement. Do you need to do that in browser first?
Yes, v3.10.5 is the current released version because reasons. You can read the thread to see them.