(44,36) Privileges not sufficient for file mess

What does this mean?

Im in the isodraft module

Do you have write privileges to the necessary folders?
The message file will be created in default folders. Generally it is C:\data\pdmsuser.

Message file for your isometric is of name mess and may be you are trying to use more than one Isodraft Session. Another possibility the last user had not properly closed out and the file is still open for editing by the previous user. Close isodraft and delete the file.

Where can I check which libary it tries to put the file?

In you IsoDraft options file there should be a path to where it's trying to right the MESS file to.

And if you do not get the filepath with only 'mess' written in the option file then:
Right Click on the PDMS shortcut on the desktop!
In the properties there will be start in location defined.