Using a non npm 3rd party library

Up until now, any 3rd party library I have worked with has been available as an npm install and everything has been pretty straightforward.

I’m now trying to utilise this library on a payment form:

and I’m not exactly sure of the best way of doing this on my payments component i.e the bit in step 3 - including the library on a component and invoking it ?

Does anyone have any guidance on what I would need to do here?

I may have worked it out - now testing.

Would be great to know how you implemented an external js script with simply a URL. Thank you in advance.