After your Workspace is created it's necessary to invite users to it. If you are a workspace creator, then you're granted Administrator role and can invite new members to this workspace. Invited users are automatically assigned a Member role and can only suggest inviting others, and the administrator has to approve this suggestion.
If you are a workspace creator, follow these steps to invite new users:
Click Invite Users link in the Leverice channel tree on the left side of the screen;
Or click on 3 dots to the left of your Workspace name and select Invite Members.
Invite using Invite link:
Send the link via email or messenger to the person you want to invite.
Invite via email:
Type in the email addresses of the people you want to join your Workspace;
A new member is invited!