To install correctly an MT5 Expert Advisor (EA) you should place the files (ex5 or mq5) in the right folder.
Follow the steps below for installing the EA correctly:
1. Go to ‘Open Data Folder’ command in ‘File’ menu of the MT5 Terminal. You can also press [Ctrl+Shift+D].
2. Open ‘MQL5’ folder.
3. Open ‘Experts’ folder.
4. Place there the file with extension ‘ex5’ or ‘mq5’ or both of them.
5. Restart the MT5 Terminal (Close it and open it again).
That’s all. Now your EA is installed and it’s ready to be used in your charts. If you need instructions for installing in MetaTrader 4 take a look at this post: How to install an Expert Advisor in MetaTrader 4 (MT4).