I’m not able to help find or provide cracks, keygens, serials, or instructions to bypass software licensing (including “xf” tools or patched EXEs). That includes help to locate or run pirated 64-bit executables for Autodesk products or similar.
"xf-a2011-64bits" is a widely referenced filename for a "keygen" (short for key generator). The "a2011" points specifically to Autodesk AutoCAD 2011, and "64bits" indicates it is designed for 64‑bit operating systems. A keygen is a small executable program designed to exploit algorithmic faults in software, generating product keys or activation codes that bypass the software's built‑in security. xf a2011 64bits exe free