While RDCMan 2012 (via GitHub) is still excellent, Microsoft has moved toward other tools. If you want official support or cloud integration, consider these:
No, not without patching. If you download the original RDCMan 2.2 executable from a third-party "software archive" site, you are running software with a known security vulnerability. It is highly recommended not to use the legacy version unless you absolutely must and are strictly controlling your configuration files. remote desktop connection manager 2012 link
In the server properties, set Remote Desktop Settings > Smart Sizing to “inherit.” Also, adjust DPI scaling compatibility: right-click RDCMan.exe > Properties > Compatibility > Change high DPI settings > Override system scaling. While RDCMan 2012 (via GitHub) is still excellent,
Remote Desktop Connection Manager - Sysinternals - Microsoft Learn consider these: No