Highlight a cell in a column if an input is matched in Google sheet

I would like to create a Google Sheets form where participants can organize themselves into groups of three. Specifically, I want a cell in the "Email List" column (which is fixed and cannot be edited by participants) to be highlighted when a participant enters their email,

I very appreciate any help.

I have searched for "Match and Highlight" using Googe Sheet from this website but no answers were helpful to my question.

>Solution :

To achieve this result you can use conditional formatting with a custom formula:

=MATCH(D2, flatten($A$1:$B$3), 0)

• D2 is the left and top-most cell of the range you need to format.
• $A$1:$B$3 is the range where you need to search for the values. Important: it has to be fixed (have $‘s in front of all parts of the coordinates).

Conditional formatting rule:

Result:

Document with the working example.