com.apple.developer.storekit.external-link.account
A Boolean value that indicates whether your app can link to an external website for account creation or management.
Discussion
If your developer account has this entitlement, add it to your app by opening the project’s entitlements file in Xcode. Add the following key and set the corresponding value to true:
<plist>
<dict>
<key>com.apple.developer.storekit.external-link.account</key>
<true/>
</dict>
</plist>