Hi @ricard! The target directory for the ROMs is correct, but be aware that there are two further components that must be added to the binaries package, for the plugin to work. I cannot comment more on this specific subject, due to emulator policy restrictions.
Also, make sure to retrieve all the possibly available ROM expansions, for the presets to be entirely selectable from the Zynthian GUI, and aligned to the plugin view on VNC.
As for this, I suggest you revise and peruse the last posts of the JV-880 thread.