No problem. You may run into some issues once in a while too where Duo won't accept the sentence structure "Have you a toilet?" and demands "Do you have a toilet?". If that happens try not to get too angry and flag it with the report option "My answer should be accepted". For some reason that sentence structure seems to be hit or miss.
The correct conjugation for "Sie" is "haben." It does not matter whether you want singular or plural.
I have = ich habe
you have (singular, informal) = du hast
he/she/it has = er/sie/es hat
we have = wir haben
you have (plural, informal) = ihr habt
they have = sie haben
you have (formal, either singular or plural) = Sie haben