Why can’t I add cash to Apple Pay by transfer from a bank account?

Apple Pay and Apple Cash are 2 different things.

Apple Pay itself holds no cash. It has no balance. It's merely a conduit for payments.

You can add funds to the Apple Cash card from a debit or prepaid card by following the steps in the support document you posted from: Add money to Apple Cash

If you are having an issue with those steps, please explain what that is. What happens when you try to add money to Apple Cash? Have you even set up Apple Cash?

Hilandluvr wrote:

My linked account is a checking acct.; when I try to add cash I’m told

I don’t have a debit card in wallet. I prefer not to use debit cards.

Solution?

As KiltedTim stated, you will need a debit card. Apple does not currently allow for linked checking accounts. You can let Apple know it's something you'd like to see in the future here:

Product Feedback - Apple

Hilandluvr wrote:

Apple Cash will only let me add money from a debit card not a linked

bank acct.

Are you saying that you can only use a debit card that isn't linked to a bank account? I didn't even know that was possible.

Hilandluvr wrote:

Apple Cash will only let me add money from a debit card not a linked

bank acct.

hilandluvr

That’s correct.

Get a debit card.