Do not deploy new systems with this client. Use the built-in ESXi Host Client (HTML5) via HTTPS, or upgrade to vSphere 7.0/8.0. If you are simply recovering old data, download the client via the official portal once, install it on a Windows 10 LTSC virtual machine, and air-gap that VM from your production network.
If you have landed on this page, you are likely managing a legacy VMware vSphere 6.0 environment. You need the standalone (often called the "C# Client" or "Fat Client") to manage your hosts or older virtual machines. vsphere client 6.0 download link
However, VMware (now Broadcom) has made this file difficult to find intentionally—because the product is dead. Do not deploy new systems with this client