From the web, you can easily log into DrChrono here. You simply need to type in your Username & Password.
From the iPad you can log in with your both your Username & Password, a Pin, Touch ID or Face ID if you have a newer iPad. You will have to have downloaded the our 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 & Password. This will be under your account settings on the iPad.