fitness on ipad

You need more that just the app.

Your iPad needs to be updated to the latest iPadOS 14.3

You need a compatible Apple Watch ( series 3 or later ) updated to its latest WatchOS version and, also, Bluetooth connected to your iPad before the iOS App Store will let you download/install the Apple Fitness+ app.

You need to have or purchase an Apple Watch series 3, or later.

No options.

iPadOS 14.3 was created specifically so that an Apple Watch can be directly paired to an iPad via the Bluetooth settings.

If you need additional assistance, you need to contact Apple Support via the Contact Support link located at the upper top right corner of every Webpage of these Apple support communities.

Best of Luck to You!