When I start duplicacy, I see this error and then it appears that the application quits

running duplicacy 2.1.0
mac 10.13.4

I started setting it up for backup to wasabi, then I quit duplicacy. When I started back up, it gets stuck on bootup, prompts me with this error message:

help!

You can run defaults delete com.acrosync.mac.duplicacy License in Terminal and then restart Duplicacy.

thank you!