I've just started a new contract and one of the client's sites uses an old 6.1.6 version of Umbraco. They were having deployment issues sync'ing content between server so I thought I'd add uSync. Being someone who has only really used Umbraco 7+, I struggled for a good hour to get uSync working (mainly due to my stupidity), so I thought I'd write a quick guide in case anyone has the same problem.
I tried installing uSync via Nuget but it didn't work, so here goes: First, head over to the uSync page here.
Scroll down to the bottom of the page and you should see the packages download section, in here find the version you want. In my case, this was 'uSync-1.6-for-Umbraco-6.1.x.zip'
Now open your Umbraco back-end and head to the developers section.
Click 'Packages' -> 'Install local package'. Tick the T&C's box, select the Zip file from your PC (you do not need to un-zip it) and hit load package.
You should see an error, detailing the package has .NET assemblies, click the 'Accept License' checkbox and click 'Install Package'. Now, if you refresh the page in the 'developer' section, you should see a little 'uSync' tab, click on it and you should now have all the power of uSYnc at your hands. To test everything worked as expected, hit the 'Export' button.
Within the webroot, you should now see a 'uSync' folder. In here you should see a lot of XML files that contain all your data. Using the import/export you can now move your data types between servers without having to manually re-add them in.