Issue: 403 Error in Bot Configuration

Good Morning,

I'm having an issue trying to set up a custom Copilot by following the tutorial: https://learn.microsoft.com/en-us/microsoft-copilot-studio/configure-sso?tabs=classic

Single-Sign On is definitely working on the custom site which I've developed but then I'm experiencing a 403 error when trying to make actual use of the Copilot bot, so that the custom website looks like the below:

Below is the error as displayed in devtools (I've put it as an image and as a JSON code block):

t
message
    :
    "ajax error 403"
request
    : {
        async: true,
        crossDomain: false,
        withCredentials: false,
        headers: {
            …},
        createXHR: ƒ,
        …
    }
response
    :
    error:
    code:
    "RegionNotAllowed"
message
    :
    "The request received in unitedkingdom but target regional bot belongs to europe. Please check BaseURI  https://docs.microsoft.com/azure/bot-service/rest-api/bot-framework-rest-direct-line-3-0-api-reference?view=azure-bot-service-4.0#base-uri." [
        [Prototype]
    ]:
    Object[[Prototype]]:
    Object
responseType
    :
    "json"
status
    :
    403
xhr
    :
    XMLHttpRequest {
        readyState: 4,
        timeout: 20000,
        withCredentials: false,
        upload: XMLHttpRequestUpload,
        onreadystatechange: ƒ,
        …
    }
    [
        [Prototype]
    ]:
    Error

I am using the HTML code of the custom website from this repo, and I tried editing the code to force the domain to be Europe and thus avoid the error above stating that the request is coming from the UK, but this doesn't seem to have done anything. Below is the change that I made to the code from this CopilotStudioSamples repository:

Can you please help me figure out what is causing this issue preventing the custom website from working?
Please excuse my lack of knowledge about web design, I'm just a humble Power Platform developer and this is all very new to me.

Thanks,

Start with the custom website HTML from the CopilotStudioSamples repository and the Direct Line BaseURI reference linked in the report. Compare the endpoint used by the site with the Copilot's regional configuration, then verify that bot requests no longer return the RegionNotAllowed 403 response.