Installing ACF withous SAP Logon?

Hi,

at customer, we have many users that do not deal with SAP Logon at all. That means they do not even have it installed on their computers. When trying to install ACF at those, we get the following error:

I really did not find any prerequisities saying that SAP Logon is required for this. Can anybody tell, what could cause the error and what could we do with it?