AutoCad will throw an error when trying to open file with a long file path, or if the file size is above certain limit. This mainly applies to files open from SharePoint.
Please add the below registry keys via RegEdit.
Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\FileSystem > LongPathsEnabled = 1
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WebClient\Parameters > FileSizeLimitInBytes = 5000000000
The "FileSizeLimitInBytes" will say "5000000000" bytes is too high, and it will auto truncate to "4294967295" bytes.
Reboot is required to apply the changes, otherwise AutoCad will continue showing the same error message until next Windows restart.