From the web, you can easily log into DrChrono here. You only need to type in your Username & Password.
You can log in from the iPad with your Username and Password, a Pin, Touch ID, or Face ID if you have a newer iPad. You must have downloaded the DrChrono EHR app from the App Store first. Please note: if you forget your pin, you can review it once you have logged in with your Username and Password. This will be under your account settings on the iPad.