Common Configuration Mistakes
Mistake 1: Wrong authentication. You add a Gmail module but you're not logged into the right Gmail account. The module connects to whichever account is set as default. Check which account you're connecting before proceeding. You can usually switch accounts or disconnect and reconnect as a different user.
Mistake 2: Missing required fields. Some actions have required fields. Email needs a "To" address. You can't save the module without filling these in. Read the labels carefully.
Mistake 3: Mismatched data types. You're trying to put a list of items into a field that expects a single value. Or you're trying to use text in a field that expects a number. You'll catch this when you test.
Mistake 4: Connecting to the wrong service. There are multiple email modules. Make has "Send an Email", "Gmail", "Outlook", etc. If you accidentally choose a service you're not set up for, the authentication fails. Pick the right one for your situation.