Fatal error during new project creation

Hi, I’m new to Unity and yesterday I installed Unity 2019 on my iMac (macOS Mojave 10.14.4 - 4.2 GHz Intel Core i7 - 32 GB of memory).
If I try to create a new project (2D or 3D) on the main drive everything is fine.
But if I try to create a new project (2D or 3D) on the external 2T disk I get an error: “Fatal Error! attempt to write a readonly database”. I receive this message during the importing assets process, as shown in the screenshot below.

Can someone help me?

Thank you
(Please excuse my not perfect English.)

Any solution? Who can help me?