Don't understand European Hockey leagues

[Eisen]

This is in part incorrect, the minimum capacity is the same 15.000 for both the first and the second league so the potential promotion in itself did not create the issue but only made an already existing one more severe. They reached an agreement which would have seen Kiel play the first season using temporary stands and then start expansion works the following summer. It has been pretty common for smaller clubs to have makeshift stadiums, for example in Mainz the old stadium was for years like that consisting only of one permanent stand. Much of the capacity can consist of standing areas, in the first league 8.000 and in the second 3.000 must be seated.

Waldhof, back in the day, had to play in Ludwigshafen because of stadium issues. When teams advance, usually a solution is found, at least in soccer.