Ensure the file inside is what you expect (e.g., a .exe for an installer or .bin for firmware). Be wary of "double extensions" like document.zip.exe .
This is typically downloaded as an APK for Android or directly from the Google Play Store rather than a ZIP file. If you found a "RTNK.zip" file on a third-party site, be cautious as it may be an unofficial bundle. Option 2: RTK Software (Engineering & GNSS) Download RTNK zip
A common download for medical imaging and 3D reconstruction is the RTK-2.7.0.zip found on OpenRTK.org . Ensure the file inside is what you expect (e