You can start testing Matic on Cargo by going to https://rinkeby.cargo.build. In order to get up and running you will need to complete the following steps:
Use MetaMask to sign up on the Cargo test site.
Add the Matic testing network to MetaMask.
Fund your wallet using the test Matic faucet.
MetaMask will be required to test Matic on the Cargo test site. After you've installed MetaMask in your browser go to https://rinkeby.cargo.build and either sign up with a new account which is linked to your MetaMask wallet, or sign in with an existing account.
We will use the Mumbai test network for this. Click on the network dropdown in MetaMask (see above screenshot) and choose "Custom RPC"
Fill in the Matic Testnet Details and click Save. Sokol will now be available in the dropdown list.
Network Name: Mumbai
New RPC URL: https://rpc-mumbai.maticvigil.com/
Block Explorer URL: https://explorer-mumbai.maticvigil.com/
Connect to the Mumbai test net in MetaMask and go to the faucet website - https://faucet.matic.network
Enter the address that you'd like to test with and request test funds.
Now you are ready to test Matic functionality on Cargo! You can connect to the Mumbai test network and deploy Matic NFT smart contracts on Cargo.