"252" in versioning often leads users to search for Microsoft Toolkit 2.5.2 vs 2.6 or 2.5.2 download . The consensus on legacy forums is: For Windows 7, stick with 2.5.2.
To use Microsoft Toolkit 2.5.2, your system should meet the following requirements:
KMS server couldn't be reached. Fix: Run cmd as admin > slmgr /skms localhost:1688 > Re-run Toolkit.