WooCommerce Stripe gateway, custom checkout with conditional fields and the dreadful "Please make sure your card details..." error message
Conflicting custom post type archive slug and page slug in Wordpress
Tl;dr CPT archive with same slug is prioritized over page - if not, flush your permalinks.
Analyzing "You do not have sufficient permissions to access this page" error in WP admin
Using poorly written plugins can sometimes leave you locked out of WP Admin due to permissions errors. Here's an approach to solving these types of problems.