If you were running the server you should see two “Duplicati.Server” items (one is the server, the other a monitor to make sure the server stays running) listed in your Task Manager, like these:
The “Missing XSRF Token” error is a known issue with the 2.0.2.1_beta version (and some of the following canary ones as well). It has mostly (fully?) been resolved in more recent canary (and possible experimental) versions.
The error itself is just related to the web GUI and does not affect the backup process. You should be able to refresh the window (such as with ctrl-F5) until the error goes away.
For more info check this out:
Where is the remote machine from which you’re trying to get access? Is it on the same network (it should work) or are you trying to connect over the Internet (likely will NOT work without router, port, firewall, etc. config)?