The issue is that you’re using a URL instead of a media link, and the URL isn’t publicly accessible. To fix this, you’ll need to create a media link. You can use third-party tools like Zapier.com or Make.com to do this.
For example, on Make.com, there’s an option to download a file from monday.com, which then generates a media link. Once you upload the file using this link, it becomes publicly accessible.
Another option is to upload the file to a shareable Google Drive folder and then add the link to your monday.com board. When you include that link in an email, it will be accessible to others.