API calls with pagination (non odata)

Hi,

I am really new to API's and am struggling to get some looping code to work to ensure all records are pulled, currently it is capped at 1000. 

I have used the example from https://community.powerbi.com/t5/Desktop/REST-API-Pagination-converting-records-to-text/td-p/681809 but am getting the following error:

Expression.Error: We cannot apply field access to the type List.
Details:
Value=[List]

The code is as follows:

let
BaseUrl = "https://api.rotacloud.com/v1/shifts?start=1569888000&end=1755875832",
Token = "SecretToken",
EntitiesPerPage = 1000,
Options = [Headers=[ #"Authorization" = "Bearer " & Token ]],
Url = BaseUrl,

GetJson = (Url) =>
let
RawData = Web.Contents(Url, Options),
Json = Json.Document(RawData)
in
Json,

GetTotalCount = () =>
let
Json = GetJson(Url),
Entities = Json[object.count]
in
Entities,

EntityCount = GetTotalCount(),
PageCount = Number.RoundUp(EntityCount / EntitiesPerPage),
PageIndex = { 1 .. PageCount},

GetPage = (PageIndex) =>
let
PageUrl = BaseUrl & "page=" & Text.From(PageIndex) & Options,
Json = GetJson(PageUrl),
Value = Json[data]
in
Value,

GetUrl = (PageIndex) =>
let
PageNum = "page=" & Text.From(PageIndex),
PageUrl = BaseUrl & PageNum
in
PageUrl,

Urls = List.Transform(PageIndex, each GetUrl(_)),
Pages = List.Transform(PageIndex, each GetPage(_)),
DataList = List.Union(Pages)
in
DataList

The below is from the API documentation, not sure if it helps or not:

In order to keep our servers happy, requests which return multiple items may be paginated. Paginated requests will include two extra response headers; 'X-Total-Count' (the total number of results), and 'Link' (containing one or more hypermedia link relations).

The possible values for the link relations are; 'next' (the link relation for the immediate next page of results), 'last' (the link relation for the last page of results), 'first' (the link relation for the first page of results), and 'prev' (the link relation for the immediate previous page of results).

You can optionally specify a 'limit' parameter to change how many results are served per page (hard limits will apply), and you can navigate through paginated results using the 'offset' parameter which lets you specify which result should be returned first, e.g. ?limit=10&offset=30 (this would return 10 results starting with record 30).

Any help would be grately appreciated, thanks in advance!