You have been asked to upload a code/link before you select an influencer so that it can help you track commissions and sales driven by each influencer.
You selected this option during the set up of your campaign under Payment section, by selecting “Unique promo code or URL per influencer to share with followers” under ‘Provide Conversion Tracking and Commission’. This can be changed if you don’t want to provide unique code/links to influencers, but will only apply to influencers who apply to your campaign after you have made the change.
If your campaign is set up incorrectly but you have an influencer who you'd like to select, then simply type in "TBD" in the code/link field and the system will allow you to make selections. You should communicate to the influencer via the Inbox that the unique code/link is no longer required for this campaign.
Don't forget to go back and edit your campaign for future influencers using the Campaign Builder.