As an external user on Plek, you are always added to one or more groups. This means that your start page and all functionalities of Plek are determined by the group(s) you are a member of.
Plek for an external user
Which group(s) you see as an external user is determined by the admin. Within these groups, you have the same rights as other group members, except for group administrators. External users can't become group administrators.
An admin can indicate if users can invite you to other groups. However, it is not possible to be added to a channel as an external user.