Hi,
What version of FMOD are you using?
So the issue is the FMOD integration needs to know about the resonance audio plugin which is outlined here: Unity Integration | Plugins - Dynamic Plugins.
The main points are adding the plugin to the FMOD Settings under the desired platforms:
Keep in mind to add plugins to
Default to be added to all platforms or specific platforms as you add them.
There is a known issue with plugins in 2.02.17 which we are aiming to fix in the next release. In the meantime, a workaround can be found here: 2.02.17 SystemNotInitializedException: [FMOD] Initialization failed : Loading plugin 'OculusSpatializerFMOD' from '__BAD PATH__/Assets/Assets/Plugins/FMOD/platforms/win/lib/x86_64/OculusSpatializerFMOD.dll' : ERR_FILE_NOTFOUND'.
Hope this helps! If you have any more questions about FMOD and its integrations please do not hesitate to ask!