No action on subscribe

Hi, have added a subscription module to site but nothing happens when I click the subscribe button.

Everything does seem to be ok in the module settings.

I do capture this event when I inspect the page and click the button -

(index):1 Uncaught (in promise) null

Whenever the button is clicked this event displays in the page inspection.

Any thoughts? Maybe Admin Tools blocking something?

Thanks

Just noticed this at the bottom of the page -

This site key is not enabled for the invisible captcha.

Was hidden by the goto top of page button.

Worked it out!

Invisible captcha was set in Config - Security.

It's only in the documentation that it says this is only for paid versions.