I would proceed with extreme caution if at all! You are running a very old version of emoncms and a lot has changed since then. I do not have experience of the sync module but I do know it will have been developed to work with much later emoncms versions, I cannot say it won’t work with your version, but I do not think any real consideration would have been given for pre v9 emoncms since emoncms underwent major revamping between v8.4 and v9.
If you wish to use the current modules and latest features you might want to consider setting up a second emoncms server and then doing a “backup” and “restore” to bring the new server up to date and then weigh up the sync module if you want other instances eg emoncms.org.
Upgrading to the latest version of emoncms will involve some work as the dashboard module and the way the feeds are referenced from them has changed, the phpfiwa feed engine is being depreciated etc.
The sync module is still in development (AFAICT) the only mention on the forum is in the Emoncms.org check your backup data
thread but that thread suggests it might not be complete.