I have the same issue... tried steps recommended by support:
I will send you some steps to troubleshoot the game
Right-click both Steam and the EA app shortcuts on your desktop.
Select “Run as administrator” for both before launching the game.
In Steam: Right-click Battlefront 2 in your Library → Properties → Installed Files → “Verify integrity of game files.”
You can also try repairing via the EA app if you see that option.
Fully exit Steam (File > Exit) and the EA app (right-click its icon in the system tray and choose “Exit”).
Restart Steam first, then launch the EA app.
Search “Edit the system environment variables” in Windows.
Open Environment Variables, and if there is a variable named “Game_DATA_DIR,” delete it and reboot your PC. This has fixed “preparing game” loop for many users.
Some users found launching from a fresh Windows profile avoids corrupted local settings. Create a new user, install Battlefront 2 in Steam, and log in to both Steam and EA with the new account.
Go to “Add or Remove Programs,” find all “Microsoft Visual C++,” choose Modify > Repair for each, especially for 2012 and 2013 versions.
Restart your computer afterward.
Disable overlays: Try disabling Origin/EA app overlays and Steam overlay for Battlefront 2 (in each launcher’s settings).
Launch directly from game folder: Go to your Steam library, right-click the game, Manage > Browse local files, and try double-clicking “starwarsbattlefrontii.exe” directly.
Install Windows and graphics driver updates: Ensure your OS and GPU drivers are up to date.
Uninstall both Battlefront 2 and the EA app, then reinstall Steam, EA app, and the game (in that order).
Nothing worked... still cant play the game.