i guess the solution is to hang a rope ladder out of your window, so people can enter without passing through the management company's private property.

people find it endlessly perplexing that private companies can put almost any condition they like upon entry to their premises, assuming the condition isn't a protected characteristic like race or something.

if your building's management company says you can only walk through the lobby, that they own, in pink flip flops and a rainbow hat, i guess you're either dressing like a clown or abseiling down the side of the fucker.

equally, if they require an accurate list of guests for insurance/fire/covid/whatever purposes, they are well within their rights to make guests sign in. in many countries, this is the norm, and is mainly done for fire safety so an accurate headcount can be passed on to authorities. this reduces their insurance and such.

tl;dr of course it's legal, you don't own the foyer and your guests don't have the implicit right to use it.