Install Keyscape ((better)) File

The large .dat file (#7 or #8) was corrupted during download. Fix: Delete that specific DAT file and the corresponding .7z part. Re-run the Download Manager to fetch only missing parts. Do not delete the whole STEAM folder.

If you bought the boxed version, it comes with a USB 3.0 flash drive containing the library. Here is how to from this drive. install keyscape