If you have Google Chrome (or Brave Browser), you can connect your Metamask Wallet to Matcha via the Metamask Wallet Extension. Once you have the Browser Extension installed, you can connect to Matcha. Here's how:
Click on the Connect Wallet button from the drop-down in the top-right hand corner.
Click on "Connect Metamask".
When the pop-up appears on your browser, click "Connect".
You can now trade on Matcha with your Metamask Wallet!
In order to connect Matcha to Metamask on a Mobile Device, it is best to use Metamask's built in browser in Metamask Wallet Mobile App.
Open the Metamask Wallet app on your mobile device.
After authenticating, click on the hamburger-menu icon in the top-left of the screen.
Select the "Browser" button.
Navigate to matcha.xyz in the URL field at the top of the page.
At the bottom-right of the page, select the hamburger-menu icon.
Click "Connect Metamask".
Start trading on Matcha!