There are the Construction point tool and the Guideline tool in Scan Essentials.
The Construction point tool makes point and the Guideline tool makes lines with 2 points.
When I click the the Guideline tool icon, its instruction appears at the bottom of the SketchUp windows.
It says I need to press ALT to add a construction line, but in fact, I just make a point like the construction point tool. So I think the instruction should be fixed into “Alt = Add a construction point”.