Welcome to the Make community!
You’ll just need to use one more function, join, to combine the array of values with ","
So the output of the map function is inserted into the first parameter of the join function, and then "," goes into the second parameter.
You can even delete the set variable module and put this directly in the HTTP module.
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
P.S.: Did you know, the concepts of about 70% of questions asked on this forum are already covered in the Make Academy. Investing some effort into it will save you lots of time and frustration using Make later!