If you have a pre-built EA you want to use on MetaTrader4 (MT4), you’ll need to copy it into the ‘experts’ folder where your MetaTrader 4 is installed on your computer. On a computer, this is usually located on your c drive.
Once that’s done, launch MT4 and expand the ‘Expert Advisors’ section on the left hand side. Your EA will be located there. Drag it onto a chart to get started, and you’ll be asked to review its settings before putting it live.