Get working https (secure connection) on all pages

General information for the website: We showcase the creative process of visual storytelling
Kind of development: Customization of existing website
Description of requirements/features: Hi there,

We want to have HTTPS on all pages on our wordpress site.

Job:
Get functional HTTPS on all pages

Success criteria:
No redirect loops
Green padlocks in all browsers
All pages are HTTPS
All functionalities are still working, such as PMPRO membership login, WooCommerce checkout etc.
Sustainable solution that works after updating plugins and theme

Setup:
www.itsoncraft.com
Wordpress
Hosted on WP Engine (business plan)
SSL certificate is installed https://www.sslshopper.com/ssl-checker.html#hostname=itsoncraft.com
SSL bought through Siteground

Installed plugins (either abled or disabled):
Amazon Web Services
Coming soon and Maintenance mode
Duplicate Post
Enable Media Replace
Hide admin Bar From Non-Admins
Intercom
Jetpack
MailChimp for Wordpress
NextGEN Gallery by Photocrati
NextGEN Gallery Optimizer
NextGEN Plus by Photocrati
Paid Memberships Pro
+ Addresses for Free Levels Add On
+ Email Templates Add On
+ Mailchimp Add On
+ Register Helper Add On
PMPRO International Addresses
Printful Integration for WooCommerce
Stripe WooCommerce Addon
Superfly Menu
SVG Support
Theme My Login
WooCommerce
WooCommerce Product SKU Generator
WooDiscuz - WooCommerce Comments
Wordfence Security
WP All Import
Wp All Import - WooCommerce AddOn
WP Bouncer
WP Offload S3
Zendesk Support for Wordpress
Extra notes: Notes: special attention to PMPRO and Theme My Login.
You will also need to sign an NDA to state that you won't share the information to third parties. No biggie.