I created a form and "opened" it then clicked share to get the sharable link. When I send it to anyone they cannot access it without reaching an error saying they must first sign in .... is this right?
When I am signed in and click the link, it works fine. When I sign out and click the link, I have the same problem.
Are you trying to provide access to the form document or the HTML fillable form? If it's the later, you don't need to share the form. Once you have opened the form, simply copy the URL that is shown in the Distribute tab. Here's the format of the link you should be sending out.
https://adobeformscentral.com/?f=<some form id>