Given it's an old farm building the walls are likely to be quite thick so the signal is probably being blocked by the wall (and quite possibly the ground given the elevated position). I think the only hope is to place the booster in a window facing the landlord's place
I'd suggest your daughter turns the booster off and tries finding a signal using the laptop outside any prospective window first and if she gets one move inside and check if it can still be received through the window. Might need to try higher than the window sill.
If she finds a signal she'll have to position the booster in the window at the height she found signal.