Can I choose the location of the temporary directories?

In the folder /wp-content/uploads of your WordPress installation, BackWPup creates temporary directories for files, which are only needed while a job is running. You can choose another folder for the temporary directories.

For this, you need write access to your wp-config.php, which can generally be found in the root directory of your WordPress installation.

Open the wp-config.php file and search for the line if ( !defined('ABSPATH') ).
Add this line before the one of step 1: define( 'WP_TEMP_DIR', '/absolute/path/to/wp/your/temp-dir' );
Replace /absolute/path/to/wp/ with the absolute path of your WordPress installation and your/temp-dir with the path to your new temp folder.
Save the file.