Within Reefmaster, I started getting error tiles that show a link the following Blog Post.

That's sad news. Not sure how badly this affects RM, but right now there's no online background maps available.

It's a shame, but the satllite imagery from MapQuest was not of the best resolution for most places. We are currently looking into a new option for satellite background, MapBox, which we might include in the future. For now, the OSM Open Cycle Map is still available in RM -this was the default in any case.
The unfortunate fact about using online satellite imagery is that, even where the license terms allow it, it is very expensive. For example, using Microsoft Bing imagery would cost around half of the cost of a ReefMaster license per user, per year, which is obviously not viable.

Understood on the licensing costs, they can be ridiculous. There's still the excellent RM option of using an MBTILE file or similar as the background image. This is what I have utilized, since I had an MBTILE saved of the exact same Open Aerial tiles :-)