I have tried repeatedly to download add-ons from your site, and every time I do, the downloaded add-on appears in a downloaded files pop-up window, with a button with "open" and "delete file" choices. I tap Open and I get error message "File could not be opened."
I don't have trouble with add-ons on Firefox or Chrome, so why would I have a problem with Opera?
I'm using Opera 21 on Android 4.4.2
Settings allow cookies to be set.
[Thread closed as a duplicate of: Extensions in Opera Mobile]