I notice you're asking about installing "ArcGIS 108" — but there is no official version (the correct versioning is ArcGIS 10.8.x, not "108").
If you encounter any issues during the installation process, refer to the Esri website for troubleshooting guides and technical support resources. install arcgis 108
To install ArcGIS Desktop 10.8 , follow these steps to prepare your system and complete the setup program. Note that ArcGIS 10.8 is in its Mature Support ArcGIS 10
You cannot download ArcGIS 10.8 from a generic software archive. It is a licensed commercial product. Legitimate sources: Minimum free disk space: 5–10 GB for application;
: Select "Define a License Manager now" and type the hostname or IP address of your license server.
: Select "Advanced (Concurrent Use)" and define your License Manager server name.