Garry's Mod Server - Friend can't see addon contents in spawn list

It seems your FastDL is not set up properly, here is how to do it.

Setting up Workshop downloads for server

1. Create an auth key http://steamcommunity.com/dev/apikey
   Use your server's IP (Without the port)

2. Create a new text file in the same location as your SRCDS.exe in your server files and rename it to start.bat then open it up with your favorite notepad (notepad.exe is default with Windows)

3. Paste the following into start.bat

   @echo off
   cls
   echo Protecting srcds from crashes...
   echo If you want to close srcds, close the srcds window and type Y depending on your language followed by Enter.
   title Server Watchdog
   :srcds
   echo (%time%) srcds started.
   start /wait srcds.exe -console -game garrysmod +map gm_construct +maxplayers 16
   echo (%time%) WARNING: srcds closed or crashed, restarting.
   goto srcds
   

4. On line 9 you may change what the default map, maximum players, gamemode, etc. can be
   (to change gamemode type +gamemode NAME where NAME is the gamemode code name, you can Google what the gamemode code names are, sandbox is default)

5. On line 9 you want to add -authkey YOUR AUTHKEY HERE

6. Now you will want to create a collection of all the addons you want your server to have by going to the Create collection page

7. Follow the on-screen instructions

8. Once you have finished, Take the URL of the workshop collection (example: http://steamcommunity.com/sharedfiles/filedetails/?id=298302791)

9. Copy the digits after the ?id= in the url (example: 298302791)

10. Now go back to the start.bat file and on line 9 type +host_workshop_collection COLLECTION ID

11. Replace COLLECTION ID with the digits after ?id= from the URL

Setting up Workshop downloads for client

1. Go to C:\GMOD SERVER FOLDER\garrysmod\lua\autorun\server
2. Create a file called workshop.lua (change the ending of a .txt file to .lua)
3. Open workshop.lua with your favorite notepad (notepad.exe is default with Windows)
4. Now locate your Workshop Addon on the workshop website
5. Take the URL of the workshop item (example: http://steamcommunity.com/sharedfiles/filedetails/?id=370857063)
6. Copy the digits after the ?id= in the url (example: 370857063)
7. Now go back to the workshop.lua file and type resource.AddWorkshop("WORKSHOP ID")
8. Replace WORKSHOP ID with the digits after ?id= from the URL
9. Go to the next line
10. Repeat steps 4-9 for EVERY workshop item

Example:

resource.AddWorkshop("123456789")
resource.AddWorkshop("987654321")
resource.AddWorkshop("192837465")

The quotation marks are important