Finding a "free" legitimate version of Microsoft Office 2010 for Windows 10 is difficult because Microsoft officially retired support for it on October 13, 2020

Microsoft Office 2010 reached its end of life on October 13, 2020. This means Microsoft no longer provides security updates, bug fixes, or technical support for this software. Using it on Windows 10 (especially the 64-bit version) poses significant security risks, as any vulnerabilities discovered after 2020 will remain unpatched. Additionally, Microsoft no longer offers official downloads for Office 2010, and any “free download” sources found online are almost certainly unauthorized, potentially containing malware, spyware, or modified code that claims “extra quality” but actually compromises your system.

No, you should not use it permanently: