Did you download the SDK?
What UI steps do you seem to automate - I’m guessing you mean “signing” but that isn’t exactly inserting a certificate.
i should automatically insert a "certificate", not "signing"!
Certificates are used for signing (and encryption) – so you have to do one or the other. Which is it?
i need a Digital Signature (with Certificate)
in german Acrobat Pro DC like this: