Concenate Text by Symbols

Hello,

I have an issue where I'm attempting to concatenated a string of text based from another list...For Example if List 2 has an "#" within the string then combine matching value within List 1 or in List 3 (I apologize if this sounds confusing), but the goal is to combined text with the value that's matched. I tried using an IF function, but ran into errors. I enclosed a spreadsheet of this issue with some notes to help clarify this issue. Any help with this would be greatly appreciated..

Thank you