Hi Penifaz,
welcome to the Apple (user-to-user) Community!
Re: "Why can’t I link Amy IPad with my iCloud storage, it keeps telling me I am out of storage
when u have plenty when I go to my iCloud in settings"
Seems iCloud is mainly a sync service for access to all your files across all your devices,
(syncs data as set up by you). iCloud can also store back-ups of your iPad / iPhone data.
Apart from using low-res photos etc. on the iPad to save space:
The storage space on your iPad can not be extended by the use of iCloud storage.
iCloud merely reflects / syncs / what is stored on your iPad ...
See: What's the difference between device storage and iCloud storage? - Apple Support
NB: If you delete an item from iPad: it deletes from everywhere it is synced.
If you delete an item from iCloud: it deletes from the device it is stored on, keeping all in sync.
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Re: "My iPad says low storage"
If you wish:
You can go to Settings > General > [Device] Storage to check storage space.
How to check the storage on your iPhone and iPad - Apple Support
It is a good idea to back up everything
Eg: to a computer or an external storage device, before freeing storage space.
To back up your data: How to back up your iPhone, iPad, and iPod touch - Apple Support
How to: Connect external storage devices to iPad - Apple Support
How to: Archive or make copies of the information you store in iCloud - Apple Support
How to make space on your iPad using recommendations:
If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support
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Re: "How to link my phone amd iPad with iCloud storage"
You can turn off or on the sync of apps and their files between iCloud and your devices.
Change which apps sync and store data with iCloud - Apple Support
Set up and use iCloud Photos - Apple Support
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If needed: Support websites (info. / support / contact options etc.)
iCloud - Official Apple Support
iPad - Official Apple Support
iPhone - Official Apple Support
All the best :-)