We'll start by assuming there are no down guy annotations in the photo. After selecting the Hardware Details tool, if down guys need to be annotated, you'll be prompted with strand measurements for each down guy as recorded by the data collection teams. These measurements are displayed in the bottom-left of the photos tab and should follow a universal top-down order, so you should be able to work sequentially starting with the topmost down guy bolt. In cases where there are multiple anchors, the top-down order applies per anchor, so make sure you're looking at the correct set of down guys. The first down guy measurement will be highlighted in orange. Click at the bolt of that down guy and set the company attribute. You should notice a checkmark appear next to that strand measurement in the bottom left and the next measurement will now be highlighted orange. Continue annotating each down guy in the same way—clicking at the bolt and setting the company information—and repeat until you've resolved all down guy annotations. You can also click on an existing cable attachment to set the down guy annotation at the same height and automatically set the corresponding company.
If down guy markers are already present in the photo, you don't need to click at the bolt to create a new annotation. Instead, simply click on the existing grey label, and it will link the marker to the corresponding strand measurement.