Please install my modified XposedInstaller(3.1.5) to properly detect Systemless Xposed.
The APK is signed by my personal key, you might need to uninstall other versions before installing mine.
If Xposed Installer app shows "Xposed is installed but not activated", try reboot the system.
The binaries are identical to builds downloaded from official links https://dl-xda.xposed.info/framework/, with the exception that app_process* is patched with the following command:
sed -i 's:/system/xposed.prop\x0:/sbin/xposed.prop\x0\x0\x0:g' app_process*
This module most likely will never get any updates in the future, since @rovo89 seems to have stopped development. This module is here for historical reasons.