find isn't going to work on a table, but it will work on the contents of a table. So Guillaume, is right that if you're looking for values in one variable, use dot subscripting.
Those strings, and the fact that you're searching for multiple hits for a single value, leads me to think you should be using categorical for the strings. And then when you get to the point when you need to find all the groups of rows in the table, not just one, you can easily use varfun or rowfun with that categorical as a grouping variable. Hard to give specific advice without knowing where you're headed.