The reason of the problems:
1. Function should look like this: saveproject("C:/NewFolder/test.tsp2");
2. NewFolder folder should be created. Function could not create new folders.
3. The reason of not saving maybe that your disk C are protected from unauthorized written. Usually on disk C could write only Administrators. Use other disk.
For example saveproject("D:/NewFolder/test.tsp2");
Best regards,
Ruslan