Set up MathWallet

Install MathWallet Chrome Extension from https://mathwallet.org

Use Testnet 'Galois L1' as example, for mainnet, please use 'MathChain L1'

Open 'Settings' - 'Networks'

Find 'Galois L1' in Polkadot category and switch ON

Switch Network to 'Galois L1'

Then you can create/import wallet and access web wallet or dappstore