You have been a forum member for over a year, by now you should know that you have to give specifics because we are not mind readers. What output are you getting when you run "pamac build slack" ? Share the output of the following.it is not installing.
i have installed slack web
pacman -Qs slack
~ slack -get That's because Slack is a command-line utilty.
You know what figure it out yourself if you aren't willing to explain it in words or give details of what problems you are actually having. The output your are sharing is the help of the command you are running, that should be enough to get you started. ~ slack -get
usage: slack [-f] ('get' | 'GET' | (('reset' | interval) command [argument] ...))
~ slack get 1 ✘
Do you see now how important in mentioning details are when you are asking a question or asking for help?!!!