What is the correct input of the Basic Auth field?

Hello,

I am on the zapier free trial subcription.

I created the following 2 step zap. The purpose is to retrieve google worksheet data, map them and process the data by a custom wordpress app.

1. Update or New Google Sheet
2. Post Webhook by Zapier

For step 2 I have trouble authenticating.

I made custom plugin code for Wordpress. Additionally, I set-up a WP application password.

In Step 2 there is an action option. There is an input field called Basic Auth. Here there is only 1 input field. Is this correct for a username and a password?

I tried the following:

1. Username:password | myname:test1234
2. Username:myname | password:test1234
3. Base64 encode value (which seems logical as there is only 1 input field)

For username I used the username of the wp-user and the password of the wp applicaton password.

But it keeps throwing 401 whatever I try.

What is the correct input of the Basic Auth field?

Do I need a webhook plugin to get this working?

Kind regards,

Wes