CW, as I understand it (and hopefully David or another Guru will chime in) as long as the association has the building insured to 80% of the replacement cost then FEMA will (through some sort of a co-insurance program) pay 100% of the partial loss. If they are insured below 80% then there is a co-insurance penalty assessed for any claims.
The coverage you need is the least of the O/S principal balance, the replacement value of the structure or the maximum allowed under the NFIP. If the associations insurance is enough to cover this you should be OK, but you need to insure the coverage is enough to cover the replacement value/O/S balance of your unit. The simplest way I know to do this is take the coverage and divide it by the number of units.
SWW, if you are taking a mortgage against an individual condo unit, I would hope there is no O/S loan to another FI on the building your condo unit is located in. But to answer your question, you as the lender on the condo unit are responsible to insure adequate flood insurance is in place if it is required.
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The opinions expressed are mine and they are not to be taken as legal advice.