i can no longer use itunes ver 12.3 using ver 17 update on iPad. Can you help

Some newer models of iPad require either a recent Mac computer with Finder - or Windows PC with the most recent version of iTunes for Windows (this only being available for Windows 10/11).

Older models of iPad can still use older versions of iTunes with older Mac computers and Windows 7.

As described, you appear to now fall in the category of a sufficiently recent iPad - and an older Mac. If you don’t have access to a suitable computer of your own, that of a helpful friend or family member will suffice. Alternatively, the technicians at the Genius Bar of your local Apple Store will be delighted to assist:

Genius Bar Reservation and Apple Support Options - Apple

If you are just need to transfer files and photos between iPad and Mac/PC, consider using iCloud.

What, precisely, are you attempting to achieve - and how? With benefit of more information, contributors may be better able to offer appropriate help or guidance.

Writing an effective Apple Support Commun… - Apple Community