Is an installation permit required for the pavilion?

The basic answer to this question is: No. A pavilion is considered a "temporary structure". Temporary structures are constructions that are intended and capable of being repeatedly assembled and dismantled at different locations. The volume of space is crucial. Each federal state has different guidelines. This varies, for example, from 30m3 in Hamburg to 75m3 in Brandenburg. Please inquire with your local municipality.