Hi Scott8850,
welcome to this Apple (user-toi-user) Community!
Re: "Web purchases : " .... Apple account is not able to do web purchases ....:
When I’m in Safari, browsing the Internet try to make a purchase at a website. "
Your Apple Account is the account you use to access Apple services like the App Store, Apple Music, iCloud, iMessage, FaceTime, and more. It includes the email address and password you use to sign in as well as the contact, payment, and security details you use across Apple services.
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Re: It tells me that my Apple account is not able to do web purchases.
An Apple Account is for purchases from Apple.
You would need to make other arrangements for web purchases that are not from Apple.
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Re: How do I fix it?"
As Apple users, like yourself, in the community, we are generally not financial or security advisers.
Eg: Check which payment methods the manufacturer(s) / merchants / offering items online can accept.
It is really up to you which of their acceptable payment method options you choose to use.
Eg: Am not an Apple Pay user myself, so am no expert:
If you have (or add) credit or debit cards in Apple Wallet:
in some countries it is possible to set up and use "Apple Pay" for web-purchases on any sites that can accept Apple Pay. Learn where to use Apple Pay - Apple Support
To see which banks participate: see if you can select your country or region within the article below.
(NB: There are links for other countries and regions)
Apple Pay participating banks in Canada, Latin America, and the United States - Apple Support
Apple Support has "how to" articles online: Eg: How to: Set up Apple Pay - Apple Support
or Make purchases using Apple Pay - Apple Support
says:
"You can use Apple Pay to pay online when you see Apple Pay as a payment option"
All the best :-)