In order for your user to connect to your business network, you will need to setup a VPN gateway. If you already owned a FortiGate, you can configure FortiGate as your VPN gateway. Depending on your need, you can configure either SSLVPN or IPSec VPN:
Correct for IPsec (standardized, mostly inter-operable with possible issues usually stemming from implementation details), but wrong for SSL-VPN. No such thing as an "SSL-VPN standard" exists. SSL-VPN is a concept ("do a VPN by wrapping traffic in SSL/TLS/HTTPS"), but everyone does it their own way. FortiClient's SSL-VPN won't work with non-Fortinet products, and neither will arbitrary third party SSL-VPN clients work with FortiGate. (unless the author specifically made effort to make it compatible with FortiGates)
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.