Hi, just downloaded the app bookmarks and previous using the password manager. What I understand and gather is that the different bookmarks and password should show a screenshot of the site in question.
But on my instance of Nextcloud, non of the bookmarks nor the password backgrounds shows and only showing a standard color or picture.
Any ideas what could be the issue?
Check your admin settings. There should be sections for the various apps that allow you to setup integration of a third-party service that will be used for creating screenshots. 
chown -R www-data:www-data /your/link/to/nextcloud/ if u upload via ftp this works most of the time when adding new addon via ftp/sftp
Under Settings > Management > Bookmarks > Preiview you can configure the Screenly API key, which is required to generate page previews.
Thanks all for the input, it was that I didn’t realize that I needed the third party integration, eg the screenly in password manager and the others in bookmarks. Works like charm now!