Saving and loading

[Snake Plissken 炎と雨]

If you have Win10 (probably with OneDrive enabled), you have to set on access privilege for the game client to this folder in Windows Defender (antivirus) first. It is notification when game is installed (or navigate to Control Panel).
Message is like this: CMLaucher.exe is not enabled to write in folder %userprofile%\OneDrive\%documents%\Eidos
Name %documents% is language sensitive, for instance "Documents" in english, and you should replace it with localized name for your language.
After installation we have 2 folders (at least):
With or rather for settings (is empty bc is blocked): %userprofile%\OneDrive\%documents%\Eidos\Championship Manager 2010 (with empty \Metadata).
With game program: %SteamLibrary%\steamapps\common\Championship Manager 2010

Run game, start new season, create manager, team, and save (game options)...
Message "Can't save". OK. Enable access to %documents% again (Windows Defender).
Your first autosave files (with settings) after "New season" creation should be in the folder:
%userprofile%\%documents%\Eidos\Championship Manager 2010\
and/or
%userprofile%\OneDrive\%documents%\Eidos\Championship Manager 2010\
Config.txt
options.CM2010-Option
personality.CM2010-Profile
and in subfolder "Filters", in my lang "Filtry"m with files:
ROZSZERZONE.CM2010-HighlightFilter
TYLKO BRAMKI.CM2010-HighlightFilter
WAŻNE.CM2010-HighlightFilter

Enter to game, use option "Save As". New folder appears: "Zapisane gry" and a file %yourseason%.CM2010-SaveGame
and also autosave %yourseason%_Autozapis.CM2010-SaveGame
But load game panel is still empty.
Create there new folder (with english name): Save Games
Copy your save file from "Zapisane gry" (this is example in my lang) to "Save Games".
You will see it immediately in the Load panel. Open it and voila :)
Ah, do this action every time you leave your game with save. Autosaving is bad idea.

To sum up, then we have 3 different problems: 1) Windows Defender, 2) potentially full OneDrive (free default version ofc) for hundreds Steam games and not only, 3) wrong saved files location (probably hardcoded but I didn't check).