I have the same problem. API is correct but not way to connect Woocommerce with Mailchimp
My sistem info is:
### Begin System Info ###
— Site Info
Site URL: https://aquadepure.es
Home URL: https://aquadepure.es
Multisite: No
— Hosting Provider
Host: DBH: localhost, SRV: aquadepure.es
— WordPress Configuration
Version: 4.9.1
Language: es_ES
Permalink Structure: /%postname%/
Active Theme: Sanzo 1.1.1
Show On Front: page
Page On Front: INICIO (#7350)
Page For Posts: Blog (#36)
ABSPATH: /home2/aquadepu/public_html/
Remote Post: wp_remote_post() works
Table Prefix: Length: 3 Status: Acceptable
WP_DEBUG: Disabled
Memory Limit: 40M
Registered Post Stati: publish, future, draft, pending, private, trash, auto-draft, inherit, wc-pending, wc-processing, wc-on-hold, wc-completed, wc-cancelled, wc-refunded, wc-failed
— WordPress Active Plugins
Akismet Anti-Spam: 4.0.1
AMP: 0.5.1
Contact Form 7: 4.9.1
Glue for Yoast SEO & AMP: 0.4.2
Hello Bar (Official): 1.0
Loco Translate: 2.0.17
MaxButtons: 6.24
Mis funciones: 1.0
Slider Revolution: 5.4.6.2
Tawk.to Live Chat: 0.3.4
ThemeSky: 1.0.8
Vikinguard: 3.1.2
WooCommerce: 3.2.5
WooCommerce MailChimp: 2.1.2
WPBakery Visual Composer: 5.1.1 (needs update – 5.4.5)
WP Force SSL: 1.3
WP Super Cache: 1.5.8
XCloner – Site Backup and Restore: 4.0.5
Yet Another Stars Rating: 1.4.9
YITH WooCommerce Social Login: 1.2.0
YITH WooCommerce Wishlist: 2.1.2
Yoast SEO: 5.8
— WordPress Inactive Plugins
Code Snippets: 2.9.4
Duplicate Post: 3.2.1
Envato Market: 1.0.0-RC2
Facebook for WooCommerce: 1.6.5
ITRO Popup Plugin: 5.0.2
Redirection: 2.10.1
Sanzo Importer: 1.0.4
SSL Insecure Content Fixer: 2.5.0
WP Mapa Politico Espa?a: 3.1.1
YITH Newsletter Popup: 1.0.5
YITH WooCommerce Compare: 2.2.2
— Webserver Configuration
PHP Version: 7.0.25
MySQL Version: 5.6.36
Webserver Info: Apache
— PHP Configuration
Safe Mode: Disabled
Memory Limit: 256M
Upload Max Size: 55M
Post Max Size: 55M
Upload Max Filesize: 55M
Time Limit: 60
Max Input Vars: 2000
Display Errors: N/A
PHP Arg Separator: &
— PHP Extensions
cURL: Supported
fsockopen: Supported
SOAP Client: Installed
Suhosin: Not Installed
— Session Configuration
Session: Enabled
Session Name: PHPSESSID
Cookie Path: /
Save Path: /home2/aquadepu/tmp/
Use Cookies: On
Use Only Cookies: On
### End System Info ###