That’s how your server action step should look like:
"exec": {
"steps": {
"name": "api1",
"module": "api",
"action": "send",
"options": {
"url": "https://apitest.authorize.net/xml/v1/request.api",
"method": "POST",
"dataType": "json",
"params": {},
"schema": [],
"data": {
"authenticateTestRequest": {
"merchantAuthentication": {
"name": "8aW2aYs7g",
"transactionKey": "582q9B5EfVtyYT4u"
}
}
}
},
....