Save a responseText to field after API Post request

I have created a code page to handle following post request: 
$.ajax({
           type: 'POST',
           url: "https://API.Endpoint";,
           processData: true,
           data: {login: "XXXXX", password: "XXXX"},
           dataType: "json",
           success: function (data) {
               processData(data);
           }
});
 
function processData(data){
 
 //Do some stuff with the data

}


I get a reponse like following: 

1. {readyState: 1, setRequestHeader: ?, getAllResponseHeaders: ?, getResponseHeader: ?, overrideMimeType: ?, ...}
1. abort: ? (a)
2. always: ? ()
3. complete: ? ()
4. done: ? ()
5. error: ? ()
6. fail: ? ()
7. getAllResponseHeaders: ? ()
8. getResponseHeader: ? (a)
9. isRejected: ? ()
10. isResolved: ? ()
11. overrideMimeType: ? (a)
12. pipe: ? (a,b,c)
13. progress: ? ()
14. promise: ? (a)
15. readyState: 4
16. responseText: "{"returnCode":"9999","return":" response generated and valid until .","returnData":null,"sessionData":"XXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXX"}"
17. setRequestHeader: ? (a,b)
18. state: ? ()
19. status: 200
20. statusCode: ? (a)
21. statusText: "OK"
22. success: ? ()
23. then: ? (a,b,c)
24. __proto__: Object

I need to save the 16. responseText to a table, more specifically the "sessionData" to a field.
The "sessionData" contains a token, which I need to use in other API calls from inside quickbase.

How can I retrieve the sessionData in Quickbase and store it to a field, using the same code page as described above ?


Thanks in advance