The Fatal: Could not find ini Error: Skyrim.ini can not be found. The INI file is missing from its default location at *\Skyrim.inierror message signifies that the INI file can not be found at that path or access is denied.
The game launcher can be started directly from a file manager like Windows Explorer without Steam to avoid game updates. Exit the launcher instead of starting the game.
If the shown game mode is wrong, start the tools in the desired game mode.
If command line arguments are used to instruct to use a non default INI path, double check the arguments are set and passed to the tools correctly.
In case existing files can not be accessed, add an exception to whatever it is that is blocking access.
Alternatively set the path to the INI with a command line argument. If the path to the INI is already set with command line arguments, make sure they have been added correctly.