Praise be to Allaah.
The basic principle is that prayers should be offered in
congregation in the mosque, where the call is given. It is permissible to
pray in congregation in the workplace if the workers going to the mosque
will lead to the work being affected. This has been discussed in the answer
to question no. 74978
With regard to praying Jumu‘ah, it is more important and the
obligation is more emphatic; it is not permissible to miss it except within
very strict guidelines, such as the risk of damage or harm, or if there is
an interest to be served for the Muslims, such as dealing with emergencies
in hospitals, and the like. This has been discussed in the answer to
question no. 36530
Based on that, you have to go to Jumu‘ah, and advise the
owner of the apartments and explain that it is not permissible to stay away
from Jumu‘ah, and he will not be harmed by the loss of a few customers; many
customers, if they find the building locked, will come back after the
prayer. You should go out to Jumu‘ah just before the adhaan, and go to a
nearby mosque where the khutbah is not too long.
And Allah knows best.