SmartStart does not need to be "installed", it is part of the hub. The mobile app is needed only to scan the QR codes that come with the StartStart devices. Here are the better docs on adding a SmartStart device using the mobile app: Z-Wave Manual | Hubitat Documentation
That being said, you can use my HE app mentioned above to manually add a SS code if you have the FULL DSK (not just the 5 digit pin). Once you have the app CODE installed from HPM, you have to install the app to your apps list. See the last section here: How to Install Custom Apps | Hubitat Documentation
Working on finding the other recent post discussing adding a code manually with my app.
Found it: SmartStart not available, version 2.4.1, ios - #35 by AMDG
