Any suggestions?
Here are a few:
The 'tutorial' uses a non standard technique to identify the segments. The segments are ALWAYS identified by letters, typically lower case, starting with 'a' at the top and proceeding clockwise (analog clock) and ending with 'g' in the middle. The Sparkfun pinout is generally correct for all devices with 10 pins as well. If you notice you can put the device in upside down and it will still function normally. As a matter of fact this is sometimes done deliberately so that two adjacent devices can have their decimal points function as a colon.
Ultimately you are going to need a lot of I/O pins. For each five digit display you will need seven pins for the segments (eight if you need the decimal point) and five more for the anodes (or cathodes). You should consider an I/O extender, possibly something like a 'Centipede Shield' centipede_shield [macetech documentation].
I suggest that you start by getting one digit functioning and display the output of a binary counter on that display. Next you should expand to two digits, and finally five digits. You should do all of this using just the Arduino at first, and then with your I/O extender.
Don