Okay, so I really wanted to try this out so I decided to give it a go on my localhost. I got one step further on my Ubuntu running Apache2 & PHP7.1
I made it into the setup, but after typing in MySQL details and having the setup daemon upgrade the tables, it told me the setup has finished the login form shows up - but there was no option to create a user during the setup 
I googled this: https://community2.invoiceplane.com/t/topic/4485/3 so now I am in the dashboard. I am getting random logouts though. For one, I cannot change the user password. When I click the button “change password” it either logs me out straight away or waits for me to enter new password twice and kicks me out when I hit the Save button.
But hey, I can live with default password. So I decided to create a new invoice group and create an invoice. But it kicks me out when hitting the save button again.
What is there I am doing wrong? Any logs I should paste?
Thanks.