You cannot simply use an old USB 2.0 thumb drive you found in a drawer. Photoshop is resource-intensive; it reads and writes data constantly. If your drive is too slow, the software will lag, crash, or fail to open.
When your computer runs out of RAM during intense edits, it uses "Scratch Disks" as temporary storage. Photoshop Portable Drive
Enter the .
Understanding the difference between these two approaches is critical for performance and security. You cannot simply use an old USB 2