Mac Mini M1 with Dockstation with 1TB SSD

Hello,

I have a Mac Mini M1 from Silicon, and actually have a too-small SSD drive in it. Now I bought a MacMini Dockstation with 1TB SSD card.

My problem is that so I cannot install OS Venture on the new 1TB SSD, I thought I have much more space.

Is there anyone who can explain to me how to do it?

Thanks in advance