If you install an app manually (not via Softaculous) you usually need to create a MySQL database first.
- Sign in to cPanel.
- Look for the Databases section and click MySQL Database Wizard.
- Step 1: enter the database name and click Next.
- Step 2: create a user with a strong password (not the same as your cPanel one).
- Step 3: assign the user to the database with All Privileges.
Write down the three values: database name, username and password. You will need them when configuring your app. cPanel prefixes the database and username with your cPanel user.