Before you can use the Polygon network, you'll have to add it to MetaMask manually. Here is how you can do so!
How to add the Polygon network to the MetaMask mobile app
1. In your MetaMask mobile wallet, tap on the menu icon.
2. Tap on Settings.
3. Tap on Networks.
4. Tap Add Network.
5. Here is where you add the network manually. You can type or copy and paste in the following information:
a) Network Name: Polygon Mainnet
b) RPC Url: https://polygon-rpc.com
c) Chain ID: 137
d) Symbol: MATIC
e) Block Explorer URL: https://polygonscan.com
6. A screen will pop up that you have switched to Polygon Mainnet. Tap Got it.
7. That's it! You've added the Polygon network to your MetaMask wallet.
If you'd like to switch networks, tap on Wallet.
8. You can scroll down to see all networks, and tap on the one you would like to switch to.
How to add the Polygon network to the MetaMask browser extension
1. Go to polygonscan, scroll to the bottom of the page, and click on Add Polygon Network.
2. A screen will ask Allow this site to add a network? Click Approve.
3. A screen will ask Allow this site to switch the network? Click Switch network.
4. Now when you open MetaMask you will see that the network is set to Matic Mainnet. This is the same as the Polygon network.