Tamil ACI is a free font available for personal use as well as commercial use. you can use Tamil ACI font for any publishing work, digital or printed media.
Downloading and Installing The Tamil ACI Font
before installing Tamil ACI font you have to download Tamil ACI font and save on your hard drive. then unzip it using any program or windows / mac default options.
then right click on the ttf files named Tamil ACI.ttf and then click install.
or you can Tamil ACI font files (.ttf) inside "fonts" folder in System Drive > Windows > Fonts folder.