When connecting authorize.net, "you must disable Shop Pay Installments to use this provider" error

[amhcphar]

Someone please help me

On my admin Setting page, when I try to connect authorize.net, I get this error message "you must disable Shop Pay Installments to use this provider"
I never used Shop Pay or Shopify Payments before.

I tried to activate Shopify Payments, deactivated Shop Pay and Shop Pay installments, and deactivated Shopify Payments completely.

Then I tried to reactivate Authorize.net 

Still getting the error.

Can someone help me with this?

The answer on the other thread does not work either for me

website is  www.thehcb.shop
No shop pay button is activated on the website either

There is this installment coding embedded on Main-product.liquid

I am currently using Dawn theme.

I removed {{ form | payment_terms }} part, and still getting the same "please disable Shop Pay Installments" error.
How to deactivate Shop Pay installments coding-wise?

<div {{ block.shopify_attributes }}>
{%- assign product_form_installment_id = 'product-form-installment-' | append: section.id -%}
{%- form 'product', product, id: product_form_installment_id, class: 'installment caption-large' -%}
<input type="hidden" name="id" value="{{ product.selected_or_first_available_variant.id }}">
{{ form | payment_terms }}

I am currently using Dawn theme.