Make sure Visual C++ Redistributables are installed
Make sure WebView2 is installed
Make sure Microsoft Edge is installed
Right click launcher.exe, select Properties and tick the unblock checkbox and apply
For error -3 or data directory error Open the Command Prompt and run icacls "%USERPROFILE%\Lexis" /grant Everyone:(F) /t /c /q
For error -4 or blank screen Try deleting the %USERPROFILE%/Lexis/Launcher folder, if that does not work, reinstall it by WebView2 by following the steps in this post.