Creating the platform account
Download the official client for your device and register with an email address or phone number you actually control. Use a real one: account recovery, and any dispute later, depends on it. Choose a screen name you are happy to be known by, because it is visible at every table and is not casually changed.
Set a password unique to this account and enable any two-factor option the platform offers. A poker account holds a balance; treat it like a banking login rather than a game login.