After starting Shrugs.app for the first time, you need to login into one or many Slack workspaces. There are two ways to authenticate against Slack: Either with a "bot token" using just the official Slack API which is the default configuration. Or using a so called "client token", which allows Shrugs to use unofficial API and behave like the regular Slack client (the latter is what most 3rd party clients do). "Client token" setups are available in the "Advanced" section of the login panel.
Using the bot token may require that your adminstrator allows the use of Shrugs.app in your workspace. Free workspaces are limited to five bot applications.

Workspace access can be tested with as many Slack accounts as you like. Make sure everything works as expected, prior purchasing a license! The free version of Shrugs.app only allows access to the #general channel plus 4 more conversations, but is otherwise unrestricted.

It is highly recommended to move Shrugs.app to the Application folders after download.