First, make sure system is updated:
sudo pacman-mirrors -f && sudo pacman -Syyu
Reboot.
For dkms you need the kernel headers. So the following command (credit to @dalto) can be used to install the headers upfront:
sudo pacman -S $(pacman -Qsq "^linux" | grep "^linux[0-9]*[-rt]*$" | awk '{print $1"-headers"}' ORS=' ')
should be replaced by
sudo pacman -S dkms git base-devel --needed
Reference:
https://wiki.archlinux.org/index.php/Dynamic_Kernel_Module_Support
Then you can install the driver
git clone https://aur.archlinux.org/rtw88-dkms-git.git
cd rtw88-dkms-git
makepkg -si