the value for --database= is the name of the database and not the project. If you are connected to Neo4j browser and if you run show databases; this will list the databases within the project
the neo4j-admin command is to be run at the command line of the OS (i.e. linux or windows) and not a command you can run from the Neo4j Browser. From the screenshot it appears you are running this from the Neo4j Browser.
@jhayes8552 open the command prompt from your Windows machine then navigate to the directory /bin folder under neo4j installer, from there you can try execute the command, as suggested by @dana_canzano. Hope this helps you to take offline backup !!!
I've never been able to get this command to work. Windows doesn't recognize the command so I'm wondering if there were some environment variables not set during installation.
Okay, I found the bin directory, just not in the place I expected it to be. I didn't realize the command was a batch file. I was looking for an executable.