If surfers have permission, they can add the app themselves. However, in a lot of cases, companies require an admin to authenticate the app first.
How to do it
First, you need to have permissions to add Slack Apps to your workspace. If you don't please ask someone who does to carry out these steps.
The Surfboard Slack App isn't listed on their App directory yet, so you need to ensure that the "Only allow apps from the Slack App Directory" setting is disabled. See this Slack guide for further details
Next, follow this link to enable the Surfboard Slack App for your workspace.
You're all done! Now surfers can install the app for themselves.