If you must control an old Mac, use a hardware KVM or a built-in "Screen Sharing" feature over a local network/VPN rather than third-party internet-based software.
Be extremely cautious of any site offering a "patched" or "cracked" version of AnyDesk for older Macs. Security Risks: download anydesk for mac 109 5 patched
Secure the correct legacy .dmg file from one of the sources above. If you must control an old Mac, use