Same for me. It's still being fetched with a plain HTTP GET behind the scenes, I found the URL by right-clicking the downloaded item in Firefox's download manager and selecting "Copy Download Link".
On further investigation it looks like the cookies
could also might be relevant. I found this using the Network tab of Firefox's page debugging tool (right click page -> Inspect (Q) -> Network Tab, then download the Invoice on Alix)
set-cookie xman_us_f=x_locale=en_US&x_l=0&last_popup_time=snip&x_user=AU|snip|snip|ifm|snip&no_popup_today=n&x_lid=ausnip&x_c_chg=snip&acs_rt=snip; Domain=.aliexpress.com; Expires=Tue snip GMT; Path=/
I wouldn't use an invoice made by editing the request to pretend to be a different country (that's legally dubious because you have arguably altered the invoice, similar to writing a fake one yourself); but it would be hilarious if that is all that is needed for them to issue you a proper invoice.