You should have had two rows of blocks on a 20x4 display.
I hope you didn't miss this line - it's several lines below the photo of the 'blocks', just above the next photo. "As mentioned, we'll not be using the RW pin, so we can tie it go ground. That's pin 5 as shown bere:" Connecting this pin to GND is not optional as the word 'can' implies, it is necessary.
If that is not the problem then we will need a cut/paste copy of the actual code you are using along (not a link to the code that you think you are using) with a photo that clearly shows the LCD <--> Arduino connections. Forget about LCD4bit.
Don