A digital certificate, also known as an X.509 certificate, contains two pieces of information:
Issuer, which is the identity of the certificate authority (CA) that issued the certificate Public key, which is the public part of the asymmetric key pair that is associated with the certificate subject

FortiAuthenticator is a user and identity management solution that provides strong authentication, wireless 802.1X authentication, certificate management, RADIUS AAA (authentication, authorization, and accounting), and Fortinet Single Sign-On (FSSO). It also offers portal services for guest management, self-service password reset, and device registration. It is not a log server or an RSSO server. Reference: https://docs.fortinet.com/document/fortiauthenticator/6.4/release-notes

HTTPS and SSH are the default management access protocols for administrative access for FortiAuthenticator. HTTPS allows administrators to access the web-based GUI of FortiAuthenticator using a web browser and a secure connection. SSH allows administrators to access the CLI of FortiAuthenticator using an SSH client and an encrypted connection. Both protocols require the administrator to enter a valid username and password to log in.

Two statements about the RADIUS service on FortiAuthenticator are true:
RADIUS users can be migrated to LDAP users using the RADIUS learning mode feature. This feature allows FortiAuthenticator to learn user credentials from an existing RADIUS server and store them locally as LDAP users for future authentication requests.
FortiAuthenticator answers only to RADIUS clients that are registered with FortiAuthenticator. A RADIUS client is a device that sends RADIUS authentication or accounting requests to FortiAuthenticator. A RADIUS client must be added and configured on FortiAuthenticator before it can communicate with it.

Online activation of the tokens through the FortiGuard network is the most secure way of delivering FortiToken data once the token has been seeded because it eliminates the risk of seed files being compromised during transit or storage. The other methods involve physical or manual delivery of seed files which can be intercepted, lost, or stolen. Reference: https://docs.fortinet.com/document/fortiauthenticator/6.4/administration-guide/372403/fortitoken