Db train tickets

If you don't see any seat numbers you probably didn't buy any seat reservations. If you want assigned seats, just buy seat reservations for the same train.

Depending on the operator and the train, you may or may not be able to select specific seats. In some cases (like ÖBB trains) you can select seats on the operator’s website but not on DB.

There is no strict connection between the ticket and the seat reservation. On the train the seat will just display that it is reserved between your two stations.

Only ICE, EC, and IC trains have seat reservations available for purchase. IRE, RE, RB trains have no seat reservations. First come, first served (seated).

And the seat reservation light goes out 5 minutes after the train departs, so if you are not sitting in it by then, it is anybody's seat.

And just to be clear, on the ICE, EC and IC trains reservations are not mandatory, you can buy a ticket and sit in any unreserved seat for that leg of the journey. I would say most of the time I do not have a reservation.

Tell us first which trains you booked, and for which dates and times. Without that we cannot say much. There are a lot of possibilities.

As mentioned by others in Germany reservations are not automatic, and live in separate universes, but your suggestion that the ticket mentions "automatically assigned" seats suggests that you did not book a domestic DB train.

First or second class?

With a 1st class ticket, a reservation is automatically included, but somewhere in the booking process you should have been asked to select seats. I assume that if you didn't, seats would be assigned and would be shown on the ticket, since in 1st class all seats are assigned. But that doesn't apply in 2nd class, where assigned seats are optional at extra cost.

If you are in 2nd class, particularly if it is a long trip, you might want to go back and reserve seats. When booking, select "seat reservation only".