Creating an app to use with Charles Schwab is currently a multi step process that takes multiple days. The steps below are for Individual Traders
Step 1: Trader API Individual
Click on API Products and select Trader API – Individual

Request Access and then wait a few days. Once you are approved, then you can create the app

Step 2: Creating The App
Click Dashboard and then Create App. Fill out the next screen like below

Click create and then you should see something like the following

You need to wait for it to be approved, which will take a few days.