Your question is a bit confusing, but I'll see if I can help:
There are 2 scanarios that I can think of here: 1 is you are buying a condo in a complex and 2 is that you own a condo in a complex and you are not buying/selling. Either way, the answers are pretty much the same.
Your "homeowners" insurance when living in a condo does NOT cover the building itself. It is more like a renters insurance, where it covers all of the belongings inside of the residence as well as liability in case something you do affects the other condo owners in the complex.
The Condo also maintains an insurance policy. This policy covers the structure of the condo.
If the condo were to burn down, the condo insurance would pay to rebuild the building, and your homeowners insurance would pay to replace all of your belongings.
Your bank may be requesting this for several reasons: 1) they are doing an audit of their files and either found something that they didn't like or they lost that document all together. 2) the building insurance expired and they are requesting an updated copy 3) they never asked for this document to begin with and now they are updating their system or trying to sell your loan to another servicer and need this document in order to sell.
Surely you can understand why it would be important for the bank to know that the building was insured. It is a requirement of the bank for your structure to be insured, and surely it is a requirement under the DCC&Rs and covenants that the HOA/Condo Association maintain this insurance at all times.
Make a copy of the request the bank sent you and forward that copy on to your treasurer or who ever is the contact person for your association and they should take care of it for you.
Hope this helped and good luck!