If you are still stuck on "Preparing Game Data," try these deeper fixes.
Click the above the Play button in the Battle.net app.
Instructions on how to check your for blocked files. Ways to reinstall the Battle.net app itself. Let me know which step you'd like to try next! Preparing game data - Technical Support - SC2 Forums
Each replay contains:
: If the game hangs after "Preparing Data," switching your region in the launcher (e.g., from Europe to Americas) can force a re-synchronization of account data. Launch the game in the new region once, then switch back to your original region.
: Corrupted temporary files can cause the launcher to stall.
The most common cause for this error is a mismatch between the language set in the Battle.net Desktop App and the actual downloaded game data.