Yes, the arrows on the board layout point to the GND layer. I don't follow your comment about pins 2 and 4.
Are you populating the balun in the placeholder with the orientation depicted in the picture, or is it vertical? See the slide attached for reference.
In addition, I'm also attaching a slide deck with the output balun placeholder with and without the balun. Slide 1 is the balun placeholder without the balun. The only connection that leads up to VPOS is the connection to the center tap. (circled in Slide 1), which is about 0.5in away from the GND pads on the balun footprint. The second slide shows a snapshot of the placeholder populated with the Johanson 1850B15B200E. We verified that there are no shorts on the board.
Follow the guidelines provided above for proper assembly. In addition, you should make sure there are no shorts on the bypass caps that hook upto the VPOS line.