Hi nqo,
Strange that your comment on Github disappeared!
I had a look at the package on Github, Eric made some change last week (apparently disabling a mail with admin-instructions during install).
Have you already created a lot of content the past week, or would it be an option to retry the install?
On the other hand, the issue mentioning “Admin 404” is still open, as is an earlier issue regarding a custom URL for admin. Maybe the app is being reworked: almost all files have been changed last week.