Quick answer: Open ClubAffili in Safari or Chrome (or the ClubAffili app on your Home Screen), go to Staking, connect with WalletConnect to the MetaMask app (or your wallet's app), approve in the wallet app, then switch back to your browser. If you come back and see a Deposit in progress card, use it to finish or close your attempt.
Before you start
The MetaMask app (or another wallet app that supports WalletConnect) installed on your phone, with your CLUB in it.
The wallet set to Ethereum, with a little ETH for network fees.
The wallet must be your payout wallet or another wallet you have verified. If it isn't verified yet, you will be asked for one free signature the first time. A wallet that is already verified is not asked again.
Steps
Open ClubAffili in Safari or Chrome, or from the ClubAffili app on your Home Screen, and go to Staking.
Press Connect wallet, choose WalletConnect, and pick the MetaMask app (or your wallet's app).
Your wallet app opens. Approve the connection, and the verification signature if it asks. Then switch back to your browser.
Press Stake CLUB. In the Create Stake window, enter the amount and choose the lock term, then confirm.
Your wallet app opens again with the transfer to the staking address shown on the Staking page. Check the amount and recipient, approve it, then switch back to your browser.
Your stake shows as confirming (Waiting for blockchain confirmations) and usually turns Active within a few minutes. Press Check now to check straight away.
Stay in Safari or Chrome for the whole process. You don't need to open ClubAffili inside your wallet app's own browser.
The Deposit in progress card
If you started a stake and went to your wallet app, you will see a Deposit in progress card on the Staking page when you come back.
Money sent: press Check to look for your transfer.
Waiting for your wallet: if you confirmed the transfer in your wallet, press I sent it. If you didn't, press I didn't send it to close it.
The club keeps track of your attempt, so it is safe if your phone reloads the page while you are in your wallet app.
If the wallet connection spins or drops
This has been reported most often with Trust Wallet. Try these in order:
Disconnect, then connect again with WalletConnect.
Use the MetaMask app instead.
Make sure the wallet is on Ethereum.
If a deposit might have been sent, go back to the Staking page and look for the Deposit in progress card before you try again, so you don't send twice.
Don't send CLUB manually from an exchange to get round a connection problem. An exchange wallet can't be verified on your account, so the transfer can't be matched to you automatically.
Related questions
It is still confirming after an hour. Open Support with the stake amount and the transaction hash (you can find it in your wallet app's activity). See My stake is still confirming (Pending) or was Rejected.
Do I lose rewards while it confirms? No. Your stake counts from the day you sent it.
Can I use a different wallet from my payout wallet? Yes, as long as you have verified it on your account. Withdrawals still go to your payout wallet. See How to connect your wallet to ClubAffili.