Your first step in using AMPL/Gurobi is to download the appropriate distribution for your platform:
amplgurobi8.1.1_mswin64.zip: 64-bit Windows distribution
amplgurobi8.1.1_linux64.tgz: 64-bit Linux distribution
amplgurobi8.1.1.pkg: 64-bit Mac OS X distribution
amplgurobi8.1.1_power64.tgz: 64-bit AIX distribution
For Windows users, choose a destination directory folder. Virtually any folder will work such as C:\AMPL or C:\Program Files\AMPL. Then copy the distribution to the destination folder and extract the contents by unzipping it.
For Linux users, choose a destination directory, such as /opt/ampl or /usr/ampl, then copy the distribution to the destination directory and extract the contents. Extraction is done with the following command:
tar xvfz amplgurobi8.1.1_linux64.tgz
For Mac OS X, simply double-click on the installer file. This will install the files into /Library/amplgurobi811 and create links in /usr/local/bin.
After the contents are extracted, you should open doc/index.html and readme files, which provide instructions for activating license and completing installation, and user guide.