Not enough information to be specific.
OBS link exists so that Elgato can continue to advertise "compatible with MacOS" and "compatible with OBS" on certain capture devices for which they don't actually provide a standard video class driver for on MacOS. Whether that applies to your device or not I don't know since you didn't actually say what it was.
Elgato's site shows download links for OBS Link on the support pages of the devices that can use it. For other devices, you either have to use their own capture software, and for some newer devices, they are supported natively on MacOS without OBS Link.