If you entered your address exactly and it shows no active connection, then it’s no a big issue unless you try to leave BT to join another ISP , in which case although you would say to them you already have a connection (ONT) already , the records would disagree and the ISP will think you need an engineer visit to fit an ONT though one is already fitted ….or you move out and someone else try’s to get a service started over the existing ONT , the same mismatch will be there and the same issues will occur.
The reason for asking about flats is they can be recorded differently to regular addresses and have a much higher probability of incorrect records, I’d guess because you say ‘where I stay’ rather than ‘where I live’ it’s Scotland where you are , and Scotland possibly has a different method of recording flats within buildings to (for example) England.
TBH , it’s no big deal until someone moves in or out of your individual address , or if (for example) your ONT is recorded as being in a neighbouring flat (that doesn’t have FTTP yet ) and if they order it , the ISP may say they already have an ONT and all the ISP needs to do is send a router out , saying the customer just needs to connect it to the ONT , but obviously that won’t be the case , and it won’t work , but that’s a potential future issue .
