I am trying to get a free app and it won’t let me because i need to “update” payment info.

If you are being asked to enter a payment method, you can try the things in this response Recommended by Apple I need to add credit to download a free a… - Apple Community which presents multiple (albeit what appear to be outdated) methods supposedly letting you avoid this. Apple's official Support Articles team currently presents multiple statements about requiring the presence of a payment method at times, even for free items. If you are encountering one of those situations then based on the documents I suspect you have no option but to enter a valid payment method if you wish to continue downloading. Read the support article Add a payment method to your Apple ID - Apple Support about how to do that. The payment method may not be charged if you also have account balance or the item is free, but the payment method has to be present. This next article lists valid payment methods for different countries but note that in this situation Apple Account balance alone apparently may not meet the requirement and you need to use another payment method until you find one that satisfies Apple's requirement (often a credit or debit card): Payment methods that you can use with your Apple ID - Apple Support .

If you have already entered a payment method, use the first link above to check it. If a message appears in red there is a problem with it. If the information is still correct and current, contact your financial institution.

* Ref.:

Add a payment method to your Apple ID - Apple Support

"To make purchases from the App Store and use subscriptions like iCloud+ and Apple Music, you need at least one payment method on file."

If you can’t download or update apps on your iPhone or iPad - Apple Support

- "You might need to have a payment method on file, even if the app that you want to download is free."

Remove a payment method from your Apple ID - Apple Support

- If you have any active subscriptions, you must have at least one payment method on file other than Apple ID credit.

- You might not be able to remove a payment method if you have a balance due.

Sign in with your Apple ID - Apple Support

- "When you sign in to the App Store and other media services for the first time, you might need to add a credit card or other payment information."

How apps, content, and subscriptions from Apple are billed - Apple Support

- You can’t charge gifts to your Apple ID balance. If you send a gift or gift card, your primary payment method is charged.

- Some subscriptions might not be charged to your Apple ID balance.

What you can buy with your Apple Gift Card or Apple Account balance - Apple Support

"Some purchases might require that you have a credit card on file, even if you use your Apple Account balance to make the purchase."

You can download free apps, but you may need to have a valid payment method on file, even if the app you want to download is free. 

Free apps has also In-app pruchase.

See -> Buy additional app features with in-app purchases and subscriptions

Buy additional app features with in-app purchases and subscriptions

See also -> Apple Media Services Terms and Conditions

Legal - Apple Media Services - Apple

so that way all my past subscriptions that I was paying for and did not know about do not charge me.

You can alsways check for sure the following Apple articles:

View your purchase history for the App Store, iTunes Store, and other Apple media services

View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support

How apps, content, and subscriptions from Apple are billed

How apps, content, and subscriptions from Apple are billed - Apple Support

If you see "apple.com/bill" on your billing statement

If you see "apple.com/bill" on your billing statement – Apple Support (UK)

because i need to “update” payment info.

See -> If you need to change or update your Apple ID payment method

If you need to change or update your Apple ID payment method - Apple Support

See also -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

fyi: Not all credit & debit cards seem to work with App Store / iTunes Store, try a different one, or preferably a credit card. If your card is not accepted as a paymenf method, you need to contact your bank.

If you have defaulted on subscriptions that you haven't properly canceled then your account has most likely been frozen by Apple.

If you want to cancel a subscription from Apple - Apple Support

You will need to speak directly to Apple Support to resolve a defaulted account.

Contact Apple for support and service – Apple Support

You usually need to add a valid payment method to your account. Even to re-download or update apps and for free apps. There are payment methods that you can use other than a credit card. You can find the acceptable payment methods for your country here;

Payment methods that you can use with your Apple ID - Apple Support

Am trying to get free apps and update but it won’t let me because I need a payment info

Hello~ Read through the prior posts here in this thread already beginning with the “Best Reply” above by *Limnos*.

~Katana-San~