Hustle unable to pull Mautic lists

Hi there,

Trying to integrate Hustle with Mautic. I've entered my Mautic URL and credentials. When I hit GET LISTS on the password field, I get an error. See attachment. Wondering if anyone else has encountered this and can share a fix.

I've been able to get Mautic working with Bloom using custom HTML code generated by Mautic forms. But, I'd love to use Hustle instead. Thanks for your help in advance.