You only need to license something if there is a patent on it. There is plenty of stuff that is "prior art" that isn't a patent, or that isn't a patent still in force, and in such cases you wouldn't have to license.
I'll assume for now that there *is* an issued patent, still in force.
Even so, you don't need a license to file a patent of your own. Patentability and infringement are two completely different things. That said, if your widget does in fact infringe this other issue patent, then when you MAKE, USE or SELL your thing you would need a license. Note that several years will probably elapse between the time you apply for a patent and the time you're granted one. So it's possible a license is premature.
Finally, you only need a license if your widget does infringe the claims of the issued patent. Reading the summary and looking at the drawings will not tell you what the claims of the patent cover. That's usually a determination best left to a patent attorney.
I'm really confused about confidentialy. You want the "patent holder" to keep your invention quiet?