The "Retromania PS2 BIOS link" is a ghost. It does not exist as a single, safe, permanent URL. The emulation community has moved away from hosting direct links due to legal pressure.
Note that there is a popular racing game called "Mantis Burn Racing" which features a "Retromania" mode, and there is a wrestling game called "RetroMania Wrestling" (which is available on PS4/5, Switch, Xbox, and PC, but not natively on PS2). If you were looking for a download of a game called "Retromania" for PS2, it likely does not exist or is a fan-made mod. retromania ps2 bios link
If you meant RetroArch (common typo), it also requires a dumped PS2 BIOS for PCSX2 core. The same legal advice applies. The "Retromania PS2 BIOS link" is a ghost