How do I confirm I am using the correct Paypal Sandbox AppID with endpoint ( https://svcs.sandbox.pa

I am trying to set up the Fundraising Plugin on a website, but am running into some trouble doing this.

I got this back from Paypal:

"In order to approve your app for live API usage, we will need to test the payment flow against our Sandbox test environment. Please provide all details for accomplishing this: URL’s, test accounts for your site, test projects, etc. I have attempted to test using the details provided, but i am seeing the error "There was a problem connecting with the paypal gateway. (CODE)560022 The X-PAYPAL-APPLICATION-ID header contains an invalid value ". Can you confirm you are using the Sandbox AppID: APP-SECRETAPPIDNUMBERHERE with endpoint: https://svcs.sandbox.paypal.com/ please?

What should I do?

There are also a TON of other questions they are asking me about the plugin too, like whether I will be accepting cross-border payments, the number of fundraisers, projects and amounts of money they each hope to raise.

It's quite a bit!