[Plugin: Duplicator] Server error in veiwing wp-admin

I installed the package but I got these error:
(Chrome)
Server error
The website encountered an error while retrieving https://mywebsite.com.au/wp-admin/. It may be down for maintenance or configured incorrectly.

In Firefox the white death screen.
The website that I’m trying to upload has 5 plugins, I don’t know if it is the cause of this. I have no idea at all.

Please help.

https://www.ads-software.com/extend/plugins/duplicator/