Checkout URL with product id

Hi!
I am adding my products to Google and I need to provide my “Checkout URL” at either an account level or product level. I am going to try to add at the account level. This will let people who search on google and want to buy a product that I have listed go directly go to the checkout cart on happypeoplepickleball.com

Here are the instructions I am trying to follow: https://support.google.com/merchants/answer/13715458#method1

I need help finding the general URL checkout template that is applicable across all of my products.
However – if there is ONLY a customized checkout or cart URL then I need a different URL (per product).

The checkout URL that I need must:

Support the HTTP GET method (which enables adding an item to the cart or checkout to allow users to complete purchase)

Direct the customer to a checkout or cart page that doesn’t require signing in.

I tried to use: https://happypeoplepickleball.com/checkout/
but the google error was:
missing required parameter: {id}

Here are more instructions:
Opting in at the account level will apply the URL template you enter to all eligible products. If you opt in at the account level, make sure you aren’t sending the [checkout_link_template] attribute in your product feed.

How do I create the correct URL?

Here is more information:
https://support.google.com/merchants/answer/13580732#productsfromfeedapi&zippy=%2Caccount-level-url-formatting

I will need to provide a standard URL template. The URL template should include the {id} parameter to ensure shoppers are directed to the correct checkout experience:

{id} (required): Associated with a product ID. Google will substitute this with the ID [id] product data attribute.

Checkout URL template example:

The account level checkout URL template can either specify the required product parameters as part of the query string or as part of the URL path. For example, if your product feed had the following attributes:

title
color
item_group_id
id

Red Google Malibu sunglasses
red
12345
12345-R

Green Google Malibu sunglasses
green
12345
12345-G

Example #1: Take users to your store’s cart page:
https://www.mystore.com/cart?productid={id}

If your store supports the above URL template, Google will then substitute {id} with your product ID from the feed. Users will be redirected to your store’s cart page to complete the purchase.

title id URL
Red Google Malibu sunglasses

12345-R

https://www.mystore.com/cart?productId=12345-R

Green Google Malibu sunglasses

12345-G

https://www.mystore.com/cart?productId=12345-G

Example #2: Take users to your store’s checkout page:
https://www.mystore.com/checkout/{id}

If your store supports the above URL template, Google will then substitute {id} with your product ID from the feed. Users will be redirected to your store’s checkout page to complete the purchase.

title id URL
Red Google Malibu sunglasses

12345-R

https://www.mystore.com/checkout/12345-R

Green Google Malibu sunglasses

12345-G

https://www.mystore.com/checkout/12345-G

Appreciate your help!!