Airtable Links

A noob here.
I have two tables on Airtable that are linked.
If the link column is filled, it all works perfectly.

But if it is empty, I get a list of all the records in the 2nd table.
How do I select 1 record from that list to link the records?
I tried to use a Choice that link to that column, but I can’t link to that column or edit it any way, including form the Date Editor.

Is this a Pro feature?