I installed Street Smart Plugin for ArcGIS Pro
I Also added the plugin: But the app is still disabled:
How to enable it?
The Street Smart for ArcGIS Pro User Manual devotes pages 3-8 to how it can be installed and how to troubleshoot that installation.
Consequently, it looks like you may have only performed a few steps from that process. I have not installed it myself, but I recommend following each step in those pages, and taking note of where anything did not work as described.