I am still using that powershell function as is today. Do you have the admin api application setup with the necessary API permissions based on the api endpoints you want to use?
I am not 100% sure on this but I think you are confusing the sections in the proxy configuration. The AD sync or LDAP sync section is under the Cloud Section and does not provide any LDAP filter methods.
Duo Security
Duo ...
Check out this function I created that will create a properly formatted request
https://github.com/StarkCaptain/duo/blob/master/scripts/new-duoRequest.ps1
$Request = New-DuoRequest -apiHost ‘■■■■’ -apiEndpoint ‘/admin/v1/users’ -apiKey ‘nnnnn’ -apiSe...