First, check if the Ubigi eSIM profile is installed on your iPad.
Go to: Settings > Mobile data > under Mobile plans: installed eSIM profile will appear as Ubigi or Transatel*
If your eSIM profile is already installed, go to step 2.
If no eSIM is installed yet, go to Get started and follow instructions for your device.
If you deleted your eSIM profil, please follow instructions on this link.
*Ubigi is a Transatel-NTT service.