Neo4j Desktop doesn't start on my Ubuntu 18

I just downloaded the Desktop version for my Kbuntu 18, and execute:

sudo chmod +x neo4j-desktop-offline-1.2.3-x86_64.AppImage

Then:
./neo4j-desktop-offline-1.2.3-x86_64.AppImage

However, it didn't start:

./neo4j-desktop-offline-1.2.3-x86_64.AppImage  
desktop-file-install is missing. Skipping /tmp/.mount_neo4j-qEseZe/AppRun.

(neo4j-desktop:2828): Gtk-WARNING **: 01:20:15.137: Theme parsing error: gtk.css:68:35: The style property GtkButton:child-displacement-x i
s deprecated and shouldn't be used anymore. It will be removed in a future version

(neo4j-desktop:2828): Gtk-WARNING **: 01:20:15.137: Theme parsing error: gtk.css:69:35: The style property GtkButton:child-displacement-y i
s deprecated and shouldn't be used anymore. It will be removed in a future version

(neo4j-desktop:2828): Gtk-WARNING **: 01:20:15.137: Theme parsing error: gtk.css:73:46: The style property GtkScrolledWindow:scrollbars-wit
hin-bevel is deprecated and shouldn't be used anymore. It will be removed in a future version
[01:20:16.0802] [info] Starting Neo4j Desktop 1.2.3 @ Linux 4.15.0-72-generic

It says 'Starting', but nothing shows up later. The first time when I started it, it gave an error message. After I restarted my computer, it ran like this, no error message, but didn't really start.

Did some search and installed:
sudo apt install desktop-file-utils

Now the messages become and not really starting:

./neo4j-desktop-offline-1.2.3-x86_64.AppImage
/home/martin/.local/share/applications/appimagekit-neo4j-desktop.desktop: warning: value "Neo4j Desktop" for key "Comment" in group "Deskto
p Entry" looks redundant with value "Neo4j Desktop" of key "Name"

(neo4j-desktop:14135): Gtk-WARNING **: 10:26:34.759: Theme parsing error: gtk.css:68:35: The style property GtkButton:child-displacement-x
is deprecated and shouldn't be used anymore. It will be removed in a future version

(neo4j-desktop:14135): Gtk-WARNING **: 10:26:34.759: Theme parsing error: gtk.css:69:35: The style property GtkButton:child-displacement-y
is deprecated and shouldn't be used anymore. It will be removed in a future version

(neo4j-desktop:14135): Gtk-WARNING **: 10:26:34.759: Theme parsing error: gtk.css:73:46: The style property GtkScrolledWindow:scrollbars-wi
thin-bevel is deprecated and shouldn't be used anymore. It will be removed in a future version
[10:26:36.0409] [info] Starting Neo4j Desktop 1.2.3 @ Linux 4.15.0-72-generic