Unable to test payment flow in sandbox for square-hosted checkout page

I am using square-hosted checkout pages by using payment links API and I can only see the preview of the payment page. It doesnot allow me to completely test the payment flow. I wanted to test the payment flow and payment webhooks in sandbox.
Even the Test Payment button is disabled in sandbox.
Can I not test the complete payment flow in sandbox and check the payment records in test account?

It seems like your test payment in sandbox includes an application fee. As mentioned in our guidelines, Sandbox does not support payment links with app_fee_money enabled.

If you need to continue testing in sandbox, please remove the app_fee_money in the test payment. You can also test your payments (with the app_fee_money) using a production account!

If I remove app_fee_money in test, will I be able to complete payment in sandbox and test the complete payment flow? Because the “Pay” button is also disabled on the preview page

You can test the payment flow for the Checkout API in sandbox using the “Test Payment” button as outlined in the page:

Select Test Payment to simulate a customer filling out the information requested on the checkout page and paying for their order. This is a one-time operation.