Import from Slack
To import your current Slack data into Rocket.Chat:
Go to
https://[your_app].slack.com/services/export
Click on Start Export
Wait until your download is ready and download it (it will be a .zip file)
Go to
https://[your_rocketchat]/admin/import/new/slack
Select "Slack" as Import Type
Choose your downloaded .zip file and wait until Rocket.Chat can read it (it can take a few minutes, depending on the size of your Slack export)
Click on Import
Deselect any items you don't want to import
At the top of the page, click on Start Importing