I thought polycam was a stand alone phone app that scanned and then downloaded as an .obj which could be imported to SketchUp. It’s a separate app from a separate company with no affiliation to SketchUp. That’s what I remember when I used to use it, unless they have developed an extension which I have never heard of. (EDIT: as @KyleB points out below, there is now a direct import extension available, but you still need the app to scan from your phone) Get Polycam on your phone, can’t remember if they still have a free version, scan and email the scan to yourself within Polycam then import to SKUP
If you have an iPad Pro the iPad version of SketchUp includes a room scanner direct to SketchUp that uses the iPad lidar to scan