[Specification] What type of slot support for ASUS PCE-AC88?
[Hardware Requirements]
PCE-AC88 is designed in accordance with PCI Express x1 (1 lane) standard. Please install PCE-AC88 into PCIe x1 slot on the motherboard in order to ensure the functionality of the wireless card.
Example of PCIe Slots on Motherboards

For more specifications, please refer to the below link:
https://www.asus.com/Networking/PCE-AC88/specifications/
How to get the (Utility / Firmware)?
You can download the latest drivers, software, firmware and user manuals in the ASUS Download Center.
If you need more information about the ASUS Download Center, please refer this link.