Not sure about the error.

But as far as the resuming goes, you could always only queue up what will fit within the limit, so that you don’t end up redownloading anything. Alternatively, I’ve found that Mega’s own windows app does resume just fine. So you could use that when you’re close to your limit.

Not great solutions, but the main thing is that mega has become ridiculously less convenient. Oh well, it was a bit too good to be true for a while anyway. Gotta pay Kim Dotcom’s astronomical legal bills, presumably.