Extract the download into your root directory (C:). This will create the following folder:
C:\MapSAR_Pro-master
Rename the folder to C:\MapSAR_Pro
You should now have the following folder structure:
C:\MapSAR_Pro
Documentation
Forms
MapSAR_Pro_Template
Tools
You can delete .gitattributes and README.md (optional). It is important that you don't have any additional folders between the root drive (C:) location and the MapSAR_Pro folder (it should look the same as in step 4).
To create a new incident, copy the MapSAR_Pro_Template to a new location.
Open the MapSAR_Pro.aprx file in the template folder in ArcGIS Pro
Switch to the "TASK" tab (bottom left). Select "Utilities", then "Create New Incident"