Send order to mail ... and print // help

Well, I use ElasticEmail.
But similar setup:

(2) Sending emails in Adalo using Elastic Email 1/2 - YouTube
(2) Sending emails in Adalo using Elastic Email 2/2 - YouTube

If you really want SendGrid, then AdaloGuy has a good tutorial:

You need to use in the Body:
https://sendgrid.com/docs/api-reference/

{
  "personalizations": [
    {
      "to": [
        {
          "email": "john_doe@example.com",
          "name": "John Doe"
        },
        {
          "email": "julia_doe@example.com",
          "name": "Julia Doe"
        }
      ],
      "cc": [
        {
          "email": "jane_doe@example.com",
          "name": "Jane Doe"
        }
      ],
      "bcc": [
        {
          "email": "james_doe@example.com",
          "name": "Jim Doe"
        }
      ]
    },
    {
      "from": {
        "email": "sales@example.com",
        "name": "Example Sales Team"
      },
      "to": [
        {
          "email": "janice_doe@example.com",
          "name": "Janice Doe"
        }
      ],
      "bcc": [
        {
          "email": "jordan_doe@example.com",
          "name": "Jordan Doe"
        }
      ]
    }
  ],
  "from": {
    "email": "orders@example.com",
    "name": "Example Order Confirmation"
  },
  "reply_to": {
    "email": "customer_service@example.com",
    "name": "Example Customer Service Team"
  },
  "subject": "Your Example Order Confirmation",
  "content": [
    {
      "type": "text/html",
      "value": "<p>Hello from Twilio SendGrid!</p><p>Sending with the email service trusted by developers and marketers for <strong>time-savings</strong>, <strong>scalability</strong>, and <strong>delivery expertise</strong>.</p><p>%open-track%</p>"
    }
  ],
  "attachments": [
    {
      "content": "PCFET0NUWVBFIGh0bWw+CjxodG1sIGxhbmc9ImVuIj4KCiAgICA8aGVhZD4KICAgICAgICA8bWV0YSBjaGFyc2V0PSJVVEYtOCI+CiAgICAgICAgPG1ldGEgaHR0cC1lcXVpdj0iWC1VQS1Db21wYXRpYmxlIiBjb250ZW50PSJJRT1lZGdlIj4KICAgICAgICA8bWV0YSBuYW1lPSJ2aWV3cG9ydCIgY29udGVudD0id2lkdGg9ZGV2aWNlLXdpZHRoLCBpbml0aWFsLXNjYWxlPTEuMCI+CiAgICAgICAgPHRpdGxlPkRvY3VtZW50PC90aXRsZT4KICAgIDwvaGVhZD4KCiAgICA8Ym9keT4KCiAgICA8L2JvZHk+Cgo8L2h0bWw+Cg==",
      "filename": "index.html",
      "type": "text/html",
      "disposition": "attachment"
    }
  ],
  "categories": [
    "cake",
    "pie",
    "baking"
  ],
  "send_at": 1617260400,
  "batch_id": "AsdFgHjklQweRTYuIopzXcVBNm0aSDfGHjklmZcVbNMqWert1znmOP2asDFjkl",
  "asm": {
    "group_id": 12345,
    "groups_to_display": [
      12345
    ]
  },
  "ip_pool_name": "transactional email",
  "mail_settings": {
    "bypass_list_management": {
      "enable": false
    },
    "footer": {
      "enable": false
    },
    "sandbox_mode": {
      "enable": false
    }
  },
  "tracking_settings": {
    "click_tracking": {
      "enable": true,
      "enable_text": false
    },
    "open_tracking": {
      "enable": true,
      "substitution_tag": "%open-track%"
    },
    "subscription_tracking": {
      "enable": false
    }
  }
}

You can remove the fields you don’t actually. Let me know how it goes and if you are still stuck.