Crispy forms throws VariableDoesNotExist error failed lookup for key [html5_required] on forms

I leave this as an "partial" answer since I do not know why or what the difference (in behavior) is but changing the call to the form in the template from:

{{ form|crispy }}

to

{% crispy form %}

got rid of the exception.

Then, as @skilled-in-blockchain mentions I can add the FormHelper to the form to make additional modifications. Thanks.