I read some documents of ArcGis restful service today, here is about the map export service: https://developers.arcgis.com/rest/services-reference/export-map.htm
I hadn’t found description about token in it. So I want to make sure what’s service you are using, and could you please let us know how to test it, document link about that should also helpful.
In our sample it require export map from http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Specialty/ESRI_StateCityHighway_USA/MapServer/export, so the requested link looks like:
You can directly view it on browser.
I think for your service it should have an URL to access it online, so we can see how the parameter need to be added in request and add it to the code like other parameters, for example:
Any information please feel free to let us know