Two-factor authentication is now required for developers with the Account Holder role in a developer program to sign in to their Apple Developer account and Certificates, Identifiers & Profiles. This extra layer of security for your Apple ID helps ensure that you're the only person who can access your account.
Two-factor authentication is an extra layer of security for your Apple ID designed to ensure that you’re the only person who can access your account, even if someone knows your password. It protects your account by requiring a password and access to either a trusted device or verification code delivered via SMS or phone call. Requiring more than just your password to access your account improves the security of your Apple ID and all personal information you store with Apple.
Only developers with the Account Holder role (formerly the “Team Agent”) in the Apple DeveloperProgram, Apple Developer Enterprise Program, or iOS Developer University Program need to enable two-factor authentication. Developers who are registered for a free account or who have other team roles are not required to enable two-factor authentication.
As the primary representative for their development team, the Account Holder is responsible for the membership and has full access to all related tools, resources, and benefits. Two-factor authentication provides an additional level of security for these accounts.
Once two-factor authentication is enabled, you’ll need to enter a verification code every time you sign in, unless you choose to trust the browser, in which case you won’t be asked for a verification code again from that computer for 30 days. You may be asked to re-verify if you reset or change browsers.
A trusted device is an iOS device or a Mac on which you’ve signed in with your developer Apple ID using two-factor authentication. It’s a device we know is yours and can be used to verify your identity by displaying a verification code from Apple when you sign in.
A trusted phone number can be used to receive verification codes by text message or automated phone call. You must verify at least one trusted phone number to enroll in two-factor authentication. This can be any type of phone number you use.
Two-factor authentication is built directly into iOS, macOS, tvOS, watchOS, and Apple websites. It supports several methods to trust devices and deliver verification codes, and offers a more streamlined user experience.
Two-step verification is an older method that uses SMS to deliver verification codes. It’s available to users who don’t have Apple devices, can’t update their devices, or are otherwise ineligible for two-factor authentication.
Enabling Two-factor Authentication
You can enable two-factor authentication on an iPhone, iPad, or iPod touch with iOS 9 and later, or a Mac with OS X El Capitan and later.
You can learn how to set up two-factor authentication for your Apple ID by viewing the support page.
No. You’ll need to use a trusted device to enable two-factor authentication for the first time. However, you can use the same trusted device for multiple Apple IDs that are enabled for two-factor authentication. Additionally, if you do not have access to your trusted device, you can get your verification code via SMS or phone call. When possible, you should use a trusted device to increase security and streamline the process.
You can check your security settings by signing into iCloud on a supported device with the Apple ID that you use for your developer account.
On your iOS device running iOS 10.3 or later
Go to Settings > Apple ID > Password & Security.
On your iOS device running iOS 10.2 or earlier
Go to Settings > iCloud. Tap your Apple ID > Password & Security.
On your Mac running OS X El Capitan or later:
Go to Apple () menu > System Preferences > iCloud > Account Details > Security.
If enabled you will see: Two-factor Authentication: On.
If not enabled you will see: Two-factor Authentication: Off and a link to turn on two-factor authentication.
https://developer.apple.com/support/account/authentication/