An administrator has a requirement to add user authentication to the ZTNA access for remote...

For adding user authentication to the ZTNA access for remote or off-fabric users, the following FortiGate feature is required in addition to ZTNA:

FortiGate explicit proxyallows FortiGate to intercept web traffic for authentication purposes.

ZTNA integrates with various FortiGate features to provide secure access and ensure that users are authenticated before accessing resources.

By using an explicit proxy, FortiGate can handle web traffic and enforce authentication policies for remote users who are not directly on the corporate network (off-fabric).

Thus, the correct feature to use for this requirement is the FortiGate explicit proxy.

References

FortiGate Security 7.2 Study Guide, ZTNA and Proxy Configuration Sections

Fortinet Documentation on FortiGate Explicit Proxy and ZTNA Integration