Log in to the client portal and select Download platforms in the top menu.
Choose your device:
Windows: select Download Windows.
iPhone or iPad: select Download App Store.
Android: select Download Google Play.
Any web browser: select Launch Web Trader to trade without downloading anything.
Install MT5 and log in with your MT5 account details. See 'How do I log in to MT5?'
There's no Mac download in the client portal. See 'Can I use MT5 on a Mac?'