First up welcome.
This issue may come down to terminology (or it might not) so here goes
When you say you want to trigger a link to the form
Do you mean an email containing all of the fields of the records of which one is an attachment (and that attachment isn’t working)
Do you mean you are trying to link to an actual form that you are trying to attach in the attachments field ? - if this is a url rather than attachment you may wish to
The former should work fine - just select the attachment field - do not continue to the field name / length etc. if you want a link in the body of the email this works to - do continue to url - but I believe here there are issues with how long this links lasts.