The developer was kind enough to give us a script that is going to look online what the version is and calculate the md5 sum.
That is awesome.
The script works with a command pup. ArcoLinux does not have that installed so we need to install it and its dependency go.
yay -S pup-git
Then we run the script and the PKGBUILD is then fixed.
Type in the terminal
and install the new package with
sudo pacman - U
Or if you like a faster way
Read more about makepkg on the wiki and/or in the man makepkg in your terminal.