Try path given by Jinje or else have you checked whether bios or bootldr is with slic 2.1. If yes, have you installed OEM matching certificate and then installed key as administrator.
No SLIC, no certificate - I wonder why it won't activate ? Have you read anything on how to activate windows ? Motherboards, other than ones for OEM machines, do not routinely contain SLIC tables. The OEM keys that are sold by other vendors besides the "Royalty OEMs" are essentially just online activation Retail keys but Microsoft "duckshove" the responsibility for service requirements to the person selling the OEM system. The keys on this forum will not work in this manner - they require an SLIC table (version 2.1 - real or emulated), the appropriate certificate and the OEM key that matches the Windows version installed. If you haven't been able to read these requirements from the helpful guides here you should probably just use a loader.