BASICALLY YOU HAVE TO HAVE MANIFEST FILE IF YOU ARE GONNA DISTRIBUTE OTA(OVER THE AIR) LIKE THIS THROUGH WEB SERVER

app.plist is a manifest file

The manifest is an XML-based property list (.plist extension) and it should contain the following six key/value pairs:

• URL

  a fully-qualified URL pointing to the .ipa file

• display-image

  a fully-qualified URL pointing to a 57×57-pixel (72x72 for iPad) PNG icon used during download and installation

• full-size-image

  a fully-qualified URL pointing to a 512×512-pixel PNG image that represents the iTunes app

• bundle-identifier

  the app’s standard application identifier string, as specified in the app’s .plist file

• bundle-version

  the app’s current bundle version string, as specified in the app’s .plist file

• title

  a human-readable application name

Using Xcode

• In the XCODE Archives organizer, select the archive that was used to make ipa

• Click the Export button, select Save for Enterprise Deployment, and click Next.

The Finder shows the exported that has an .ipa extension.

• Review the build options, and click Next. check Include manifest for over-the-air installation

• enter details about your web server in the Distribution manifest information dialog that appears, and click Export.

• Enter a filename and location for the iOS App file, and click Export.

YOU HAVE TO RENAME THE PLIST AS app.plist AND COPY TO

https://location.company.com/sites/mobile/Files/Mobile/deploy/

DIY

If you don't want to go through the tedious xcode process then here is the easiest way

Here is the sample manifest file content you can edit it contents according to the keys as I have explained earlier and save it as app.plist and copy to

https://location.company.com/sites/mobile/Files/Mobile/deploy/

 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
   <!-- array of downloads. -->
   <key>items</key>
   <array>
       <dict>
           <!-- an array of assets to download -->
           <key>assets</key>
           <array>
               <!-- software-package: the ipa to install. -->
               <dict>
                   <!-- required.  the asset kind. -->
                   <key>kind</key>
                   <string>software-package</string>
                   <key>url</key>
                   <string>http://www.example.com/apps/foo.ipa&lt;/string>
               </dict>
               <!-- display-image: the icon to display during download. -->
               <dict>
                   <key>kind</key>
                   <string>display-image</string>
                   <!-- optional. icon needs shine effect applied. -->
                   <key>needs-shine</key>
                   <true/>
                   <key>url</key>
                   <string>http://www.example.com/image.57×57.png&lt;/string>
               </dict>
               <!-- full-size-image: the large 512×512 icon used by iTunes. -->
               <dict>
                   <key>kind</key>
                   <string>full-size-image</string>
                              <!-- optional. icon needs shine effect applied. -->
                   <key>needs-shine</key>
                   <true/>
                   <key>url</key>
                   <string>http://www.example.com/image.512×512.png&lt;/string>
               </dict>
           </array><key>metadata</key>
           <dict>
               <!-- required -->
               <key>bundle-identifier</key>
               <string>com.example.fooapp</string>
               <!-- optional (software only) -->
               <key>bundle-version</key>
               <string>1.0</string>
               <!-- required. the download kind. -->
               <key>kind</key>
               <string>software</string>
               <!-- optional. displayed during download; -->
               <!-- typically company name -->
               <key>subtitle</key>
               <string>Apple</string>
               <!-- required. the title to display during the download. -->
               <key>title</key>
               <string>Example Corporate App</string>
           </dict>
       </dict>
   </array>
</dict>
</plist>

P.S

Make sure your website is configured to support the following two MIME types in Web server

• .ipa application/octet-steam

• .plist text/xml

After doing this if you have trouble installing the application please refer this link it'd be helpful to you

Hope this helps :)