Error when exporting form entries

[Nico-AP]

When I try to export submitted form entries in the admin, I get the following error:

Traceback (most recent call last):
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
response = get_response(request)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\utils\decorators.py", line 130, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\views\decorators\cache.py", line 44, in _wrapped_view_func
response = view_func(request, *args, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\contrib\admin\sites.py", line 232, in inner
return view(request, *args, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\views\generic\base.py", line 70, in view
return self.dispatch(request, *args, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\formtools\wizard\views.py", line 244, in dispatch
response = super().dispatch(request, *args, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\django\views\generic\base.py", line 98, in dispatch
return handler(request, *args, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\formtools\wizard\views.py", line 302, in post
return self.render_done(form, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\formtools\wizard\views.py", line 358, in render_done
done_response = self.done(list(final_forms.values()), form_dict=final_forms, **kwargs)
File "C:\Users\user\Project\Code Base\venv\lib\site-packages\aldryn_forms\admin\views.py", line 96, in done
response = HttpResponse(dataset.xls, content_type=content_type)

Exception Type: AttributeError at /control/aldryn_forms/formsubmission/export/
Exception Value: 'Dataset' object has no attribute 'xls'

In my project I'm using Django 3.2.4, Python 3.7.9 and Django-CMS 3.9.0 with the following applications and middlewares installed:

Installed Applications:
['mainpage.apps.MainpageConfig',
'djangocms_admin_style',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.sites',
'cms',
'menus',
'treebeard',
'sekizai',
'easy_thumbnails',
'mptt',
'djangocms_text_ckeditor',
'aldryn_apphooks_config',
'parler',
'taggit',
'taggit_autosuggest',
'meta',
'sortedm2m',
'djangocms_blog',
'absolute',
'aldryn_forms',
'aldryn_forms.contrib.email_notifications',
'emailit',
'filer']

Installed Middleware:
['cms.middleware.utils.ApphookReloadMiddleware',
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'django.middleware.locale.LocaleMiddleware',
'cms.middleware.user.CurrentUserMiddleware',
'cms.middleware.page.CurrentPageMiddleware',
'cms.middleware.toolbar.ToolbarMiddleware',
'cms.middleware.language.LanguageCookieMiddleware']