I made two file of HidMapperSettings, so I can switch them out if need to be. you should not install the standalone in the same folder as the steam’s version. Standalone has different folder structure.
One for my Steam
<InstallLocation>g:\Steam\steamapps\common\Elite Dangerous Horizons</InstallLocation>
Other for my Standalone
<InstallLocation>G:\Program Files (x86)\Frontier\EDLaunch\Products\elite-dangerous-64</InstallLocation>