I note that your property is located in a block of 20 flats.I presume that a community has been established and normally the community takes out insurance on the building block and common areas.This is a payment which should have been clearly defined to you during your period of physical occupation and paid probably on an annual basis.The apartment owner should take out insurance to cover fittings within apartment-kitchen fittings,bathroom fittings,marble tiled floors etc etc which are expensive to replace and classified as part of buildings by my insurance company ( I have read that this classificatin is common in Spain) ,contents insurance to cover furniture etc and accept public liability cover which will probably be included at no extra cost.The cost structure of insurance policies is such that the best option for an apartment owner might be to take out a normal building and contents insurance policy,rather than seek a policy which excludes external building on the basis that it is covered by community policy-a normal policy might be available at the same cost as a more complex individually tailored policy.
Insurance companies are notoriously reluctant to insure contents only
I note that a number of properties in your block are bank repossessions and it is almost certain that banks would ensure that any of the properties on their books
are appropriately insured
You appear to have excellent local contacts and I just wished to mention the community insurance aspect in case you were unaware of it