2) Always verify the released note of the target FMG , as an example ,please take a look into the page 18 of FMG6.0.2 released note. It includes the list of all FGT (and other supported devices) which are supported by this FMG.
3) Also remember FMG manages FGTs based on ADOM versions, for example, FGT which is running on 6.0.2, must be managed by ADOM 6.0.
4) You may also verify the device compatibility via FMG itself . Use diagnose dvm supported-platforms list.
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.