full_code_newsletter_embed

###############
## This is just for trying to get the newsletter sign-up form on a new page, not the other issue I mentioned
## This is literally all I added
###############

# views.py
from newsletter.models import Newsletter
 class EmbedNewsletterSubscribeView(TemplateView):
     template_name = 'testnewslettersubscribe.html'
     def get_context_data(self, **kwargs):
         context = super(EmbedNewsletterSubscribeView, self).get_context_data(**kwargs)

         newsletter = Newsletter.objects.get(slug="bla")

         context['newsletter_form'] = NewsletterForm(newsletter=newsletter)

         return context

# urls.py
path('testnewsletter', views.EmbedNewsletterSubscribeView.as_view(), name='testnewsletter'),

# testnewslettersubscribe.html

{% extends 'base.html' %}
{% load static %}
{% block title %}Thank you{% endblock %}
{% block content %}
<div class="container">
<h1>Thank you!</h1>
<h2>Your data was successfully submitted.</h2>

<div class="row" style="background-color:red; height:300px"></div>
<div class="row">
    <div class="col-lg-4 col-md-4 col-sm-12 col-xs-12"></div>
        <div class="col-lg-4 col-md-4 col-sm-12 col-xs-12">
<form enctype="multipart/form-data" method="post" action="/newsletter/<newsletter-name>/subscribe">
            {% csrf_token %}
            {{ form.as_p }}
            <p><input id="id_submit" name="submit" value="{% trans "Subscribe" %}" type="submit" /></p>
        </form>
        </div>
            <div class="col-lg-4 col-md-4 col-sm-12 col-xs-12"></div>
</div>

</div>


{% endblock %}

The form is in the context as newsletter_form, hence you should render {{ newsletter_form.as_p }} instead of {{ form.as_p }}.

@dokterbob sorry I didn't see this until now, usually GitHub gives me an email when you respond but it didn't so I didn't notice this! I changed it, but we still have the issue of newsletter = Newsletter.objects.get(slug="bla"). What are we trying to match for the slug, the user id or something?