scdoc is probably available in your Linux distro's package manager, and aerc is designed to be packager-friendly - so eventually the idea is that most users will apt install aerc, rather than build it themselves.
This issue comes from tcell, which has a baked-in terminfo database. I'm also not sure about the state of the terminfo database in general on OSX... in any case, I plan on improving terminfo support in tcell at some point.
Also, I had to run it as:
On OSX, otherwise got: