Is it possible to put a login and password on the generated link?

the reason is that anyone WHO has this link can send a mail through it:-)

is there a workaround

It is currently not possible to password protect the form link.

You can however embed it in your website and protect access to the page using a login interface that way only authorized users can access the form and submit data using it.

If you are not referring to the form link, I presume it could the thread link for your posted answer. Normally when creating a thread you have the option to set it as private this way only you and the support team can be able to view the thread and post updates to it.