I currently have two Mac Mini's. A 2018 with a 500GB HD and a 2012 with a 1TB HD. I am trying to connect the 2 mini's together in order to use the 1TB on the 2012. It seems easy enough. Thunderbolt 3 to Thunderbolt 2 adapter. I have a "Some Commented" status message but not connecting. Two mini's sitting 6" apart. How can I make a connection?
From what I have read, It seems easy but I am definitely missing something?

Help.....Please
From what I have read, It seems easy but I am definitely missing something?

Help.....Please