Make sure you are using Chrome browser to go on Lootex website since MetaMask is a Chrome extension.
Step 2. Tap the "Connect Wallet" in the upper right corner
Step 3. Select MetaMask
Step 4. MetaMask extension will pop up, login with password or backup phrase
Step 5. Once the wallet is logged in, it will show "Connected", then click Done
Step 6. Check the upper right corner of Marketplace, if the wallet address appears, it means success!