Finding which barn door hardware mounting type is correct is not hard, you just need to make a few decisions first. All mountings fall into two categories, Wood and Glass.
Glass Side Mountings uses bolts that attach thru the side of the door. It usually comes with special bolts that are made to attach to glass doors but can be used on wood doors. You can use Glass Mounting Brackets on a wood doors by drilling thru the face of the door. But glass doors have to be ordered with the holes in the glass, they can not be drilled on site because tempered glass will break due to the heat of drilling it. This type of rail is usually used for showers doors because it is stainless steel and will resist rusting.
Wood Top Mounting uses a top mounting bracket that mounts with screws into the top of the wood door. These mountings do not require any special ordering directions and are usually used in bedrooms, bathrooms and hall access doors.
Wood Side Mounting uses a side mount bracket with wood screws or threw bolts depending on the weight of the door, The holes are typically smaller than glass side mounting holes because of a gamete.
Both types of mountings use a overhead rail system and will probably require professional help to install.