Method for creating Category Group landing pages
2nd Revision:

The category group field layout is for categories within that group. Categories groups do not have fields assigned to them, only to the categories within a group.



1st Revision:

To get the fields of a category group, set the category like so:

{% set group = craft.categories.group('suitability').one() %}


And use fields:

{{ group.someFieldHandle }}




Original Answer:

To retrieve the category:

{% set slug = craft.app.request.segment(1) %}
{% set category = craft.categories.group('suitability').slug(slug).one() %}


Then use its fields or related:

{{ category.title }}
{{ category.somePlainTextField }}
{% set entries = craft.entries.relatedTo(category).all() %}


It would be better to set the template for the category on the category group settings page.

Set the URI to /suitability/{{ slug }} and the template to /shop/category.twig
Then you can just use the category in the template without having to set it by getting slug and pulling the category from the group. Also, this allows you to point multiple category groups to the same template if their template will be similar.