Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Giacomo,
Thank you for posting in Microsoft Office Community.
The main requirement to install Office 365 on iPad is you need an iPad running iOS 7 or later. So, you won’t be able to install on iPad running iOS 6.
For more information you may refer to the section Install Office for iPad appsmentioned in the link below:
For further queries, reply and we would be happy to assist.
Thank you.