Fix Driver Setup Error 126

If the 5.5.4 setup DLL cannot load CTL3D32, use the verified Microsoft file below. Close ODBC Administrator and ASQL first, then open elevated 64-bit Windows PowerShell:

$download = Join-Path $env:TEMP 'ctl3d32-microsoft.dll'
Invoke-WebRequest -Uri `
  'https://msdl.microsoft.com/download/symbols/ctl3d32.dll/3005CC7211000/ctl3d32.dll' `
  -OutFile $download
$expected = '6896C1F21CC9A5BC17E2E2FB645669AE708CB378C63E5EEF11B3E95527F3DA32'
if ((Get-FileHash $download -Algorithm SHA256).Hash -ne $expected) {
  throw 'Download checksum differs.'
}
if ((Get-AuthenticodeSignature $download).Status -ne 'Valid') {
  throw 'Windows has not verified this file signature.'
}
$target = Join-Path $env:WINDIR 'SysWOW64\CTL3D32.DLL'
if (Test-Path $target) {
  Copy-Item $target ($target + '.before-' + (Get-Date -Format 'yyyyMMdd-HHmmss'))
}
Copy-Item $download $target
Get-AuthenticodeSignature $target | Format-List Status, SignatureType

The verified Microsoft file is version 2.31.000, 27,136 bytes, with a Valid Microsoft Windows catalog signature. Put it in SysWOW64. If an earlier attempt placed CTL3D32 beside dhsetup.dll, preserve that copy in a backup folder outside the driver directory; that location caused a system-directory warning in the native setup dialog.

Retry the original 5.5.4 installer setup dialog. Expected result: the missing-DLL error is resolved. Then apply the 6.2.1 compatibility-driver recipe and verify the DSN's actual driver path. The original setup dialog configures the original driver; saving it after the compatibility setup can replace that setup. Use setup-554-compatibility-driver.ps1 as described in the driver recipe to preserve the required Dharma 14 path.