If you have mods installed or are just configuring your server, you might want to check the logs to see how things are going. Here's how you can easily check the current and previous log.
1. Open the File Manager.
2. Double click factorio-current.log
3. These are the most recent server logs. For example, this server needs a token set up.
4. To view a previous log, you can open factorio-previous.log