I recently got this monstera albo cutting (see photo) and noticed pretty much immediately that the aerial root appeared to be rotten (black and squishy). I cut off as much of it as I could and placed in sphagnum moss to root. Also, the ends were black and rotten so I cut that off and put cinnamon and wax on it. It's been about two weeks and this is how the previously rotten area looks. It's not squishy but it is black in color. I'm worried it's rotten. Should I cut off more? Or am I overthinking it? I appreciate any suggestions/tips!

I think that there are probably 1000 posts about this very subject on the NGA site in forums like Propagation, Houseplants and Ask a Question. There is a lot of great info on those, you can do a search and find the answers to your question easily.

Welcome to the forum! Always nice to see new members