You can try this formula then
=LOOKUP(2,1/(A2>=BB!$A$2:$A$17)/(A2<=BB!$B$2:$B$17),BB!$C$2:$C$17)
Enter it as normal. You don't have to enter it as array.
And also you should make a helper column to "erase" the #N/A instead of putting it into an ISERROR, because it will just make the formula calculating twice.
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