PublicSamples/EchoBot: deployment fails

I want to deploy PublicSamples/EchoBot exactly as per the README.md:
https://github.com/microsoftgraph/microsoft-graph-comms-samples/blob/master/Samples/PublicSamples/EchoBot/README.md

However,
when the deployment code attempts to execute the following:
https://github.com/microsoftgraph/microsoft-graph-comms-samples/blob/master/Samples/PublicSamples/EchoBot/ADF/ext-DSC/DSC-BotServers.ps1#L805-L806
that is

Import-Module $psscriptroot\..\..\bin\DscExtensionHandlerSettingManager.psm1
$ConfigurationArguments = Get-DscExtensionHandlerSettings | ForEach-Object ConfigurationArguments

I get the error message:
Get-DscExtensionHandlerSettings: The term 'Get-DscExtensionHandlerSettings' is not recognized as a name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

The VM on Azure has

• Ms Windows 10.0
• PowerShell version 7.4.1

See

Note: potential duplicate of https://github.com/microsoftgraph/microsoft-graph-comms-samples/issues/552

Start with the EchoBot README.md deployment instructions and the referenced DSC-BotServers.ps1 lines 805-806, then inspect DscExtensionHandlerSettingManager.psm1 and the PowerShell 7.4.1 environment. Done means the deployment can resolve Get-DscExtensionHandlerSettings and proceed without this error.