@davea @Vinod Kumar
Thank you for your reply, I think I found the problem. For some reason, I need to open google through Shadowsocks (VPN). The new version of Enpass (6.0.0) will be interfered by Shadowsocks in the redirect, resulting in the software not responding in time.
I just did an experiment. First open the Enpass in the case of Shadowsocks. After getting the authorization of the dropbox, then I closed Shadowsocks and clicked the "redirect" button. Enpass was successfully received, but unfortunately, if I Open Shadowsocks again, dropbox sync will report error: 204056.
if I change the cloud to google drive, after I click the "redirect" button, Enpass will go into a crash state, I guess it may be caused by the inability to access google.
I will ponder over it again, thank you again for your help.