The API is not intended to change maps that are already processed and hosted on Maps Made Easy. It is for submitting new jobs without having to go through the manual upload process. The idea is that you would be hosting the data in some other way on your own.
Please be sure to read the overview so you know what to expect:
https://support.dronesmadeeasy.com/hc/en-us/articles/216520863-API-Overview