No legitimate open-source programming software exists for the TC-508 due to proprietary communication protocols. CHIRP (a popular open-source radio programmer) does not support this model.
Now you can modify:
Occasionally, older versions of programming software are archived at archive.org . Search for "Hyt TC-508 software." These are typically safe but may lack support for modern Windows versions. Hyt Tc-508 Programming Software Free Download
Assuming you have done your due diligence and chosen a source, here is the generic process. Note that software version names may vary (e.g., TC-508_CPS_V5.03 or Hytera_Hyx_Series). TC-508_CPS_V5.03 or Hytera_Hyx_Series).