Your SSD may not be recognized because it needs to be formatted before use. Follow these steps based on your operating system:

For macOS:

1. Open Finder and go to your Applications Folder.
2. Launch Disk Utility from the Utilities folder.
3. Under External, select the SSD.
4. Click on Erase at the top of the Disk Utility application.
5. Choose the desired format (APFS for Apple devices or exFat for compatibility with Apple and Windows).

For Windows 11/Windows 10:

1. Open File Explorer and navigate to This PC.
2. Right-click on the SSD under Devices and Drives.
3. Select Format...
4. Choose NTFS (Windows Only) or exFat based on your requirements.