Shopify application expert help

I am looking for a developer who is an expert at both Shopify and Shopify applications, and who is familiar with the following specific Shopify application: AAA Recurring Membership [link: [login to view URL]] We have successfully used AAA Recurring Memberships for about a year now. In the last month, we've started having a lot of issues with their sign up page. Memberships are managed through [login to view URL], which is integrated through the app. The problem we have been having is that customers will often be redirected to the "404 Page Not Found" page when they complete the sign up page, rather than being having their account fully created. Sometimes, this error happens to 100% of customers and AAA support will fix it. However, every day now it happens to at least 2-3 customers regardless of what we do. I have tried talking to AAA about this but they don't know how to help. Is there anything I can try doing on my end to fix this problem? Could the issue be related to my Shopify theme code itself? Thank you.