AutoLogin of Nextcloud (Snap) after Start

First of all: I am not a programmer and my knowledge on Linux is that of a beginner. In January 2019 I have changed all my computers and notebooks to Xubuntu.
My actual wish is to have an auto login in my Nextcloud client. After starting my Xubuntu, I want to start Nextcloud without having to log in with password. Nextcloud client is installed as snap.
I have read this thread: How to autostart a snap of a desktop application?
and I understand, that it is not possible, to autostart Nextcloud on system start.

On my desktop computer, I achieved auto login in Nextcloud by installing the password manager Seahorse. I had nothing else to adjust and it worked immediately after reboot.
On my notebook, which has a very similar installation of Xubuntu and Nextcloud, it made no difference, whether to install Seahorse or to set gnome keyring components to autostart.

I have not the technical knowledge to compare the both computers and their settings, to find out, how I can achieve my wish. It would be even more fantastic, if I could autostart Nextcloud and combine it with auto login.
Any ideas out there?