Try to export to server
The machine where Tableau Desktop is installed requires only 250MB minimum free disk space and so the 500MB size of the "My Tableau Repository" should be sufficient.
Please bear in mind that when you take an extract, Tableau Desktop, as well as some data engines, create temporary files as part of the process. These files are placed in the operating system’s temporary files folder. By default on Windows systems, this folder is called TEMP, and it is located on the computer’s C: drive.
The TEMP folder might need as much as the square of the final size of the extract. For example, a 32GB extract may require up to 1024GB (1TB) of disk space to create the extract.
For more information, see Changing the Default TEMP Location for Creating Extracts.