Run the CPUID.Patch.bat to create the Atilla.dll,
make sure all game files are in this path: Steam\steamapps\common\Total War Attila\
run the launcher.exe from the launcher folder while you are logged in steam client.

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Alternate encyclopedia crash fix method:

add the Attilb.exe (not the Attila.exe) as a non-steam game to steam, then run it from steam library.
with this method you can put the game folder anywhere you want.