While using Fill & Sign tool from Acrobat desktop application, a message is shown on the left saying that " You do not have access to this service. Please contact your IT Administrator to gain access, or try to sign in with an Adobe ID."
You can successfully use Fill & Sign through any browser without any issues. The message as shown in the figure is thrown only while using it within Acrobat.
The solution is to enable the Document Cloud Services on the machine by changing the value of the following registry key:
[HKLM\Software\Policies\Adobe\<product name>\<version>\FeatureLockdown\cServices] bToggleAdobeDocumentServices=dword:00000000