Hi @SangJun Lee,
I'm unaware of such compatibility matrix. I believe there is none, because it is not usual to install AnyConnect to servers, so they officially test it only on client OS.
In general, whatever OS Microsoft supports, Cisco is following Microsoft on that one. E.g. because Microsoft said Windows 7 is no longer supported, Cisco is also saying the same for its SW, but this doesn't necessarily means that it will not actually work on Win7.
Kind regards,
Milos