I think you're not supposed to pay the mayor at that point, maybe it's an unfinished route, maybe it's an anti-cheating thing (I assume it's nearly impossible to gather 200k without exploiting the maid exploit) you can continue the quest line by talking to Nanami outside the town hall when your innocence is higher than 30
edit:
from the dev:
"If you're lower than 40 Innocence by day 21 you cannot unlock 7 more days and east side currently. Currently I've been thinking of free play but not sure If I will ever add it. "
the exact cap is supposed to be 40 but I've tried 30 and it worked, 25 didn't, so the dev might have made a mistake in either the comment or the code, but what happens with innocence lower than 30/40 is not implemented or completely thought out yet