I can not launch the game after I updated to Mac OS Catatlina.
Any advice?

I assume (but can't be sure, since I don't have MacOS) that Colonization has not been updated to DOSBox 64 bits yet. You can do it yourself or wait for GOG to do it.

You can download DOSBox from the official site: https://www.dosbox.com/download.php?main=1

I have the same problem. GOG help please. I am addicted to this game.

I just got an update flag for Colonization, but no changelog (yet). Could a Mac user check if they updated tthe DOSBox build to work on MacOS Catalina?

I updated earlier in the week on my MBP 15 running Catalina and can confirm it is again working. Still no changelog but the dosbox looks to have been updated to 64bit.

Cheers