Note the upgraded forum! If you are experiencing issues logging in, you may need to reset your password which should send an email. If the email doesn't arrive, be sure to check your spam folder just in case.
The documentation for the Forms module is absolutely wrong for how to manually echo the CATPCHA.
The docs say
"Special Hidden Fields
If you are using your own HTML code, you may need to include 2 additional hidden fields with values—return_url and form_url. There is also an "__antispam__" field that automatically gets generated and can be outputted automatically. Below is an example of what you can include in your own blocks.
It took us far longer than it should have to solve this. First there's the '"__antispam__" field' part. So we thought it was a variable of __antispam__ then we noticed $__antispam___field has three underscores between antispam and field. So we tried with three underscores. We tried with 'field', without 'field' both with two and three underscores. Finally we found and looped the $fields variable that has '__antispam__' to then find out it had a property 'field'.
<?php echo $fields['__antispam__']['field']; ?>
Fix your documentation please.