
Definitely take a read down below to see what's changed in El Capitan, and if disabling SIP makes sense for your setup. When you boot back up, you'll have a working adapter!. From the top bar, select '', then 'Restart'. From the top bar, select 'Utilities' and then 'Terminal'.
Let go, and wait for your computer to boot into recovery mode.
As soon as the screen goes black, hold down 'Command' and 'R' until you see a black screen with an Apple logo and a white progress bar.
6 Connect a network cable to the Ethernet port on the adapter.Steps to get your adapter working if you just upgraded to Mac OS 10.11 El Capitan. 5 Connect the USB connector on the adapter to an open USB port on your desktop or laptop computer. 4 When installation is complete, click Restart to restart the computer and finish the installation. 3 Click Install, then when the confirmation message appears, click Continue Installation. You may be prompted to enter your system username and password during installation. 2 When the installer screen opens, click Continue to start the installation, then follow the instructions to complete the installation. The driver setup driver setup dialog box opens. On the driver CD, locate and click AX88772.dmg. 1 Insert the driver CD into the optical drive of your computer. 5 Connect a network cable to the Ethernet port on the adapter. 4 Connect the USB connector on the adapter to an open USB port on your desktop or laptop computer. 3 When the installation is complete, click Finish to restart your computer and finish the installation. For other situations, you must install the drivers from the CD. It allows you to use the adapter's basic functions without installing the drivers. Note: Windows 10 and Windows 8.1 have a built-in driver. 2 Click on your operating system, then follow on-screen instructions. Note: If the software does not run automatically, locate and double-click Run.exe on the driver CD. 1 Insert the driver CD into the optical drive on your computer. Or, attach an external disc drive to your computer. Note: If your computer does not have a disc drive, you can download the driver from Search for your model number (NS-PU98505) to find the driver on the product page. The adapter does not need to be connected for the software to install. Note: The driver software must be installed before you connect the adapter. QUICK SETUP GUIDE for Insignia NS-PU98505
Drivers, Firmware & Software: File(s) - (English). Insignia NS-PU98505 USB 2.0-to-Ethernet Adapter - Use Manual - Use Guide PDF.