Make sure your channel moderation settings allow posting links in chat, otherwise only VIPs and above can post wip download links. Request codes obtained from the dedicated website can always be used but it might not be reliably online 24/7.
Examples:
!wip
prints a help message in chat
!wip e5a5bb
using a request code obtained from http://catse.net/wip
!wip https://cdn.discordapp.com/attachments/9106712553161/9165053429928/Example_Wip.zip
using Discord
!wip https://drive.google.com/file/d/1rcs9V_aq1kBjNhAQUdFz7f7kvWR/view?usp=sharing
using Google Drive
!wip oops
removes users most recent request from queue
After someone has requested a wip, press the WIP button to download it: