a direct link is: https://aicrowd-production.s3.eu-central-1.amazonaws.com/task_dataset_files/clef_task_24/d656e03e-0ab0-46b7-adaf-613db7eb57e0_PlantCLEF2020%20training%20dataset.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAJ6IZH6GWKDCCDFAQ%2F20200210%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20200210T170131Z&X-Amz-Expires=604800&X-Amz-SignedHeaders=host&X-Amz-Signature=a69489970c89563d4e30441800762bedbd6888541aeaf69cb753aba7d64940ec