Version 1.0.5.8 does not support the encryption key system at all. It works for very old FIFA 18 versions (pre-patch), but crashes instantly with the latest FIFA 18 patch.
This article provides the definitive guide to understanding why this error happens, the various failed "fixes" circulating online, and—most importantly—the to permanently resolve the encryption key issue in 2025.
Relaunch Frosty Mod Manager to generate fresh, working settings files. 3. Update to the Latest Frosty Toolsuite
Delete the ModData folder located inside your main FIFA 18 directory, then hit in Frosty to force a fresh regeneration. Pro-Tips for Managing Your FIFA 18 Mod Library
If you successfully past the encryption key prompt but encounter subsequent stability issues, consult the table below for rapid fixes: Error / Issue Root Cause