I have a "Billy Basic" question to ask on what I need to do to achieve the below

So here is my dilemma.

We use a website host in the UK that doesn’t really seem to want to development their building block type e-commerce platform to suit its users.

Been waiting nearly 2 years for them to implement the below (and I am left wondering is it really THAT hard even though I have very limited knowledge?):-

Since the UK left the EU, there are several options to post items into the EU.

I would basically, at this stage, like to be able to link to the Parcel2Go API and query/download the cost of sending a parcel within a weight band and within a certain size to all EU destinations. This will essentially get me the BASE PRICE which I can then enter into my website manually.

I have noticed that the price to Belgium has dropped by 50 pence in the last two weeks. I only want customers to pay the price we pay and not a penny more ideally.

Because of the way our host does delivery methods, it has meant that I have had to create a complex spreadsheet to calculate the VAT due to each and every country on top of the base price.

Currently, I have to go into Parcel2Go and pretend to book a parcel of the weight and size to get a base price for 5 different weight bands across 27 different countries and then populate those base prices manually into our website. It’s a time consuming task.

Here is the link to their page which asks me to add the application name:-

https://www.parcel2go.com/myaccount/api/add

I am no doubt wrong here but obviously Postman is the app I want to use but it is not linked to my website.

The question is what do I specifically need to read up on to understand what I need to do. I have a list of endpoints in the documentation and swagger (whatever that is)

Any advice for a dummy would be really appreciated.

I have a feeling that this could simply end up being a rabbit hole that I’ll spend hours and days upon and not get anywhere.

I used Postman used years ago to try and access the Amazon API. Couldn’t even get past the SHA stage!!! I think I spent 3 weeks trying to understand it.

UPDATE:

I have now been able to create credentials. That along has taken me a full 71 minutes to sort. Should have taken me a minute!!!