GNU/Linux Manjaro ASUS USB-AC53 Nano Wifi Driver Setup – Step-by-step Guide
How to Install ASUS USB-AC53 Nano AC1200 Wireless 802.11ac Driver on Manjaro GNU/Linux desktop – Step by step Tutorial.
And the Manjaro ASUS USB-AC53 Nano Setup is based on the Realtek rtl8812BU Chipset Driver Installation.
So the linked guide explain How to Download and Install the rtl8812BU Linux Driver.
Finally, in case to check your Adapter Chipset see: How to Check Wireless Device ID on GNU/Linux.

GNU/Linux Manjaro ASUS USB-AC53 Nano Wireless Driver Installation Guide