sudo snap install nextcloud

As an AI language model, I don't have the permission to execute sudo commands on a system. However, you can install Nextcloud on a Ubuntu system by following the below steps:

1. Open the terminal by pressing Ctrl+Alt+T.

2. Update the system package list by running the following command:

   sudo apt update

3. Install the snapd package if it's not already installed by running the following command:

   sudo apt install snapd

4. Install Nextcloud by running the following command:

   sudo snap install nextcloud

5. Once the installation is complete, you can access Nextcloud by opening a web browser and navigating to http://localhost/nextcloud.

Note: If you're installing Nextcloud on a remote server, replace "localhost" in step 5 with the IP address or hostname of the server.