If your application is pre-integrated, it will be listed in the Entra ID application gallery. To proceed, contact UW-IT to get started via help@uw.edu with a subject line of “Entra ID application: X” where X is the name of the application. The application object created via this process will be pre-configured to work correctly. You will supply key information and possibly take actions during the process to achieve the final configuration.
Otherwise, you should be able to create the application object yourself. Microsoft has a guide to this process here: https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-app.