Yes, due to the size of the exhibition halls, there are no restrictions in this regard.
The general requirements of occupational health and safety apply during the set-up/dismantling phase. Here in particular, the usual obligations apply with regard to conducting a risk assessment in accordance with the German Occupational Safety and Health Act (Arbeitsschutzgesetz) and the general obligations to provide training.
The general measures in effect during set-up/dismantling include the provision of disinfectants and the obligation to wear medical mouth nose protection if minimum distancing cannot be maintained during work. Further information can be found on the website of the Federal Institute for Occupational Safety and Health (www.baua.de; Corona Occupational Health and Safety Regulation (Arbeitsschutzverordnung); SARS-CoV-2 Occupational Safety Rules).