我在一个网页上有一个链接，应该允许用户从链接下载存折文件，但是当在iPhone上的Safari中单击该链接时，我收到以下错误消息：

Safari cannot download this file.

我在这里读过类似的Q& A，MIME类型设置为application/vnd.apple.pkpass。该文件可以在Windows手机上下载。
有什么建议可以解释为什么会出现这种情况，以及如何解决这个问题，以便用户可以访问存折文件？
pkpass包含以下文件：

icon.png
logo.png
strip.png
manifest.json
pass.json
signature

manifest.json示例：

{
  "icon.png": "fa6b59072ae5c8163c903d8c8b5f2e4a45fbd49b",
  "logo.png": "3165c9be22cbf76e2b3118972dabaef8918390f5",
  "strip.png": "5d15c45f543e8088c227fc54a6c01d1f9f0b1db3",
  "pass.json": "0f536b34a6b73a7799aae43ff9861dde45a6dfc6"
}

pass.json的例子：

{
    "passTypeIdentifier":"pass.com.XXXX.sampleticket",
    "formatVersion":1,
    "serialNumber":"TIC1000000518",
    "description":"XXXX",
    "organizationName":"XXXX",
    "teamIdentifier":"W9XR4FBDD4",
    "logoText":"Dragon Bay",
    "foregroundColor":"rgb(0,0,0)",
    "backgroundColor":"rgb(255,255,0)",
    "labelColor":"rgb(0,0,0)",
    "voided":false,
    "eventTicket":{
        "headerFields":[],
        "primaryFields":[],
        "secondaryFields":[{"key":"activity",
            "label":"11/20/2015 12:00 AM",
            "value":"One Day at the Museum"
            }],
        "auxiliaryFields":[],
        "backFields":[{
            "key":"terms",
            "label":"Terms & Conditions",
            "value":"XXXX"
        },
        {
            "key":"contact",
            "label":"XXXX",
            "value":"XXXX"
        },
        {
            "key":"legal",
            "label":"Legal",
            "value":"XXXX"
        },
        {
            "key":"notes",
            "changeMessage":"%@","label":"Notes","value":""
        },
        {
            "key":"lastUpdated",
            "label":"Last Updated",
            "dateStyle":"PKDateStyleMedium",
            "timeStyle":"PKDateStyleShort",
            "isRelative":false,
            "value":"2016-01-08T19:00Z"
        }]
    },
    "barcode":{
        "format":"PKBarcodeFormatPDF417",
        "message":"1000000518",
        "messageEncoding":"UTF-8",
        "altText":"1000000518"
    },
    "authenticationToken":"0123456789ABCDEF",
    "webServiceURL":"XXXX/passbook.svc"
}