When it comes to self hosted cloud storage Nextcloud is definitely the best option. It's fully open source, and allows you full control over your server. You can, of course, create your own user accounts and manage access too. There are a couple of options when it comes to setting up Nextcloud on Ubuntu. You can use Docker or you can follow the traditional install method. Either one will work. The Docker method will probably work better if you don't want to configure and manage the entire server yourself.
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-install-nextcloud-on-ubuntu-18-04-bionic-beaver-linux