Hi! Not sure if you're the one that join the discord but try this!
IF YOU HAVE PESTIVES CRASHES OR UNABLE TO CONNECT, FOLLOW THE GUIDE BELOW

1. Restart Steam and Computer

Needless to say, restarting is always the first thing to try. Please restart Steam and then repeat the downloading/upgrading. If the Steam disk write error persists, restart your computer.

2. Clear Download Cache

Clearing the download cache of Steam will force the Steam client to flush locally cached configuration data and acquire it from the Steam server again.

Please follow this path to do the clean: Steam > Settings > Downloads > Clear Download Cache

3. Repair Library Folder

The Steam Library contains all your installed games which should be writable by all users so as to download or update properly. However, sometimes Steam game update stuck because the user permissions changed and need to be refreshed.

Please follow this path to do the repair: Steam > Settings > Downloads > Steam Library Folders > Right click on folder > Repair Folder

4. Verify Local Files

Bad hardware, software crashes, and power surges can corrupt the game folders. You can use Steam to verify the integrity of these files and fix them if necessary.

Find Game in Library > Right click on Properties > Local Files > Verify Integrity of Game Files

5. Clear local Squad cache:

(It will reset your key bindings/user settings)

C:\Users$USERNAME\AppData\Local\SquadGame and DELETE THE FOLDER NAMED "SAVED"

6. The final straw:

Uninstall the GC mod and re-install it. Once re-install, reboot your machine.