makepkg -si --skipinteg

 You can manually install a package that cannot be installed from the package manager in Arch Linux.

To do this, download the mirror of the package in AUR.

Open the pkgbuild file with a text editor. Update the version of the file at the address that cannot be downloaded.

Open the command line in your current directory.

Use the 'makepkg -si' command. It may give a validation error, in which case use the 'makepkg -si --skipinteg' command.

A file ready for installation will be created and it will ask if you want to install it.