Go to https://app.involve.me/payment-accounts, choose between Test Payment Accounts and Live Payment Accounts, click on the Link Account button and in the dropdown select Square. Follow the prompts to connect an existing account or create a new a Square account.

You can use the account that is not in live mode to test your payments.

After you have connected your Square accounts, you can then use them to take payments in forms by drag & dropping the Collect Payments content element in the editor on the Thank You / Outcome pages of a specific funnel.

From the Collect Payments element, select the Payment Model you want to use (“Subscription & Recurring Payment” or “One-time Payments”), then select the appropriate Payment Account.