I think ManageOnTap.dll is a very old DLL? Generally speaking, the answer to your query is "no". If you are part of a large or government organisation, please work with your NetApp account team to find out if there are options to make it a "yes", but it would be uncommon.
You can verify any unsigned DLLs in archives at time of download by reviewing SHA1 signatures on the download page, which is served by our SSL signed website. If your organisation is doing SSL MITM, that's a risk you have to take.