Error while saving file in groundplex

I have setup groundplex on my stand alone linux machine and able to run pipeline there.
I am able to save file on cloud itself. But when I change the path to file:///myfile.json then it gives error. I am trying to save the file on groundplex linux machine. Below is the error. Please look into this and advice

Possible reasons can be failure in URL connection or file access denial, detail: /test6.json (Permission denied)

That path is the root of the file system, which the snaplex software likely does not have access to (hence the Permission Denied error). Maybe try writing into /tmp. So, something like file:///tmp/myfile.json.