The 64-bit requirement is key. Since around 2017, Microsoft has strictly enforced on 64-bit versions of Windows. Any driver without a valid digital signature from Microsoft cannot be installed by default. The SPRD U2S Diag Driver is almost never properly signed.
Troubleshoot > Advanced options > Startup Settings > Restart to "Disable driver signature enforcement". Use Device Manager Device Manager and select your PC name at the top. Action > Add legacy hardware Sprd U2s Diag Driver For Windows 10 64 Bit
enables communication between your PC and Spreadtrum devices, allowing tools like ResearchDownload or UpgradeDownload to detect your phone. The 64-bit requirement is key
(Note: Verify checksums and virus-scan downloaded files before running.) Sprd U2s Diag Driver For Windows 10 64 Bit
