On the one hand, there is the regional ticket, which allows you to travel on buses in and around Flensburg, and on the other hand, there is the state-wide semester ticket, which allows you to travel on public transport throughout Schleswig-Holstein as well as Hamburg (Ring A & B).
You can find more information about the local and state-wide semester ticket on the pages of Aktiv-Bus Flensburg and NAH.SH.
How do I order my semester ticket?
You can get your semester ticket in digital form or as a paper ticket.
Information about the different ticket forms and how to order the respective ticket can be found at following site of NAH.SH