Ifcdata Sync Client on Ubuntu Script
You need to mark the script as executable to run them from the file manager:
Right click on your .sh file and select Properties:

In the Permissions tab, check Allow executing file as program:

Close the Properties window and double-click the file. A dialog will pop up giving you the option to run the script in a terminal:

Manual Installation
Step 1 : Open up a terminal window on your Ubuntu xx.xx machine and add the necessary repository with the command:
sudo add-apt-repository ppa:nextcloud-devs/client
Step 2 : Once that command completes, update apt with the command:
sudo apt update
Step 3 : You're ready to install with the command:
sudo apt install nextcloud-client
That's it, the client is installed.