I'm not sure if COUNTIF is the correct function, but I've tried many
different functions and combinations of functions but can't seem to get the
result I want.

I have a column that contains multiple user id's from 2 different sites
(with duplicates). **Also, the column is on a separate sheet** I have a
list/array named "ID" that contains only the user ID's from my site.**on the
current sheet** I want to count the number of files my site completed by
searching the values in column C of sheet 2, comparing them to the values in
"ID" and add them.
So, if the value of USER ID is in "ID", add to the counter.

Can anyone help?