Look for the ESXi 6.0 section to find the vSphere Client (C# Client) installer, typically named VMware-viclient-all-6.0.0-xxxxxxx.exe .
On the welcome page, look for the link that says . vsphere client 60 download high quality
vSphere 6.0 reached its end-of-life years ago. In modern versions (vSphere 6.5 and later), the desktop client was replaced by the web-based vSphere HTML5 Client Official Downloads: Look for the ESXi 6