Square with uneven lights per side

Hi, I made a square pillow but the lights I used are very close together. I have 300 LEDs in the strip, but I only have 5 rows horizontal and 5 rows perpendicular (60 LEDs per row). I’m not sure how to map this as I am very new to Pixelblaze. So far I’m just having fun with treating it as one long string, but I’d like to be able to use 2D patters as well since it is a square layout.

Thanks in advance!

Oh, and is it safe to run this just off the USB plug into the board? It’s a Pixelblaze V3 Standard XL.