Get Text output used in a RESTful request

Hello everyone,

if you could help, I have a problem with automating these two test cases:
in the first one, I fill in a website form and there’s a popup with my created credentials which I copy using Get Text and store as variables (clientId, clientSecret);

in the second one – a POST request – I want to pass the obtained variables so that I can get a client token.

However, when I send the following request:

{“oxd_id”:{{oxdId}},“client_id”:{{clientId}},“client_secret”:{{clientSecret}},“op_host”:"*****************", “scope”:[“uma_protection”]},

the response is:

Unable to parse HTTP body- error occurred :: 'SyntaxError: Unexpected token { in JSON at position 11\n at JSON.parse ()\n (…)

I know the call works in Postman, but how to automate it in Katalon? I’ll be grateful for your help!