Ok, I have done what you told me:
-Here I make a 'GET' call with a fetch for the token and the response saves it in a variable called 'Get':
-Then here I make a retrieve list of that association that contains the header response data:
-Here, I do a find on that list so that it finds a member that is the same as the token and creates an object called ('X_CSRF_Token'):
*The message that appears in the image, contains the verification that it really brought me a token.*
-So in the 'POST' call I pass the value of X_CSRF_Token as a header parameter:
-In the POST, I am requesting a JSON using 'Custom request Template':
Even so, I keep getting the error '403' and I don't know why. I am making the same call in Postman and there it works fine.