afterstep binary package in Ubuntu Focal arm64

 AfterStep is a window manager based on FVWM which attempts to emulate
 the NEXTSTEP look and feel, while retaining the configurability of its
 predecessor. Note that this window manager makes extensive use of the
 color palette. If you have only an 8-bit color display, it will run
 as packaged, but you may want to modify the configuration to use fewer
 colors.
 .
 AfterStep is a continuation of the BowMan window manager project, but
 the name was changed to reflect the desire that it do more than
 simply emulate and become a valuable window manager in its own right.

Source package