Here is what someone from Mijireh responded with:
Sometimes certain web hosts are not set up to allow page slurp to work. When that happens you will need to slurp the page from inside your Mijireh account.
First, make sure the page you are trying to slurp is publicly available on the internet. You may need to change the status from private to public.
Next, log into your Mijireh account and go to Settings => Checkout Page (top right of screen)
In the “Select your e-commerce platform” drop down choose “custom”
Enter the URL to the page you are going to slurp and click the “Slurp It” button.
Then you will see a progress bar appear showing the status of your page slurp.
If you have any other questions, please let me know.
-Benjamin Rojas
Mijireh Support