I have tested with the recompiled version, the entry in the settings now appears ok, but still no login box nor authentication site page

Is there a log file anywhere?
On the other computer - on both computers actually, about the @ sign, I just have noticed that I cannot enter it in any field in MusicBee actually: so it's not only this plugin. Can you reproduce that on your end? I have a French keyboard, it that matters...
Thanks again