One of the things to note that it is possible that they've already sold their IP to another company (or in talks to do so). Some other company may then object

One of the things to note that it is possible that they've already sold their IP to another company (or in talks to do so). Some other company may then object to your use of the licensed material in violation of their exclusive license for the IP. As noted with the Spiderman fun, IP may not be simple. Some other organization may already own part of the IP from another deal (e.g. Sony owning Spiderman and MCU as part of Marvel Studios / Disney not being able to use Spiderman as a character until a deal was reached).