WixQuietExec Fails in WiX 5

Question

I have a very simple .wxs file that should just write text to a file by executing a DOS command. It fails with the error: "There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run." Here's my .wxs file:

<Wix
  xmlns="http://wixtoolset.org/schemas/v4/wxs"
  xmlns:util="http://wixtoolset.org/schemas/v5/wxs/util"
  >
  <Package
    Compressed="yes"
    InstallerVersion="500"
    Manufacturer="Acme"
    Name="Test"
    UpgradeCode="da08e63d-6cad-4941-a412-54457ef0c937"
    Version="1.0.0.0"
    >
    <Binary
      Id="WixUtilExtension"
SourceFile="C:\Users\ak109755\.nuget\packages\wixtoolset.util.wixext\5.0.2\wixext5\WixToolset.Util.wixext.dll"
    />
    <CustomAction
      BinaryRef="WixUtilExtension"
      DllEntry="WixQuietExec"
      Id="MessageBoxAction"
      Impersonate="no"
      Return="check"
    />
    <DirectoryRef Id="AcmeDir">
      <Component Id="InstallerExecutable" Guid="2addbefe-1b0a-4a19-8c75-e5fa0a359f44">
        <CreateFolder/>
      </Component>
    </DirectoryRef>
    <Feature Id="MainApplication" Title="Main Application" Level="1">
      <ComponentRef Id="InstallerExecutable"/>
    </Feature>
    <InstallExecuteSequence>
      <Custom Action="MessageBoxAction" Before="InstallFinalize" Condition="1"/>
    </InstallExecuteSequence>
    <MediaTemplate EmbedCab="yes"/>
    <Property
      Id="MessageBoxAction"
      Value="echo 'hey' >>c:\temp\hey.txt"
    />
    <StandardDirectory Id="ProgramFiles64Folder">
      <Directory Id="AcmeDir" Name="Acme"/>
    </StandardDirectory>
  </Package>
</Wix>

I don't know what I'm doing wrong here, and I haven't found any documentation for this for WiX version 5.