UK PayPal setup for ShopperPress (and probably other themes as well)

I’m trying to set up PayPal on a shop, and am somewhat confused. I can’t find any documentation but to be fair, it’s probably a moving target. That said, I’d appreciate some help, please.

PayPal, on the API screen says this:

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API Access

An API (Application Programming Interface) allows PayPal software to communicate with your online shop or shopping cart.
Setting up API permissions and credentials

Choose one of the following options to integrate your PayPal payment solution with your online shop or shopping cart.
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The two options are:

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Option 1 – Grant API permissions to a third party to use certain PayPal APIs on your behalf.

Choose this option if:

You are using a pre-integrated shopping cart, hosted by a third party
Your website is hosted and managed by a third-party service provider
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and
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Option 2 – Request API credentials to create your own API username and password.

This option applies to:

Custom websites and online shops
Pre-integrated shopping carts running on your own server
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My question here is, do I need either of these options, and if so, which one?

I host my own websites, on my own servers, BTW.

Cheers, Laurie.