Install ipa over link

Question

I have a Flutter App and want to make a website to install the .ipa for the latest build on their iPhone. I have a manifest. plist file with all the information like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>items</key>
    <array>
        <dict>
            <key>assets</key>
            <array>
                <dict>
                    <key>kind</key>
                    <string>software-package</string>
                    <key>url</key>
                    <string>https://www.dropbox.com/scl/fi/something/my-app.ipa?rlkey=some-key&dl=1</string>
                </dict>
            </array>
            <key>metadata</key>
            <dict>
                <key>bundle-identifier</key>
                <string>$ident</string>
                <key>bundle-version</key>
                <string>1.0.0</string>
                <key>kind</key>
                <string>software</string>
                <key>title</key>
                <string>$title</string>
            </dict>
        </dict>
    </array>
</dict>
</plist>

and a link to my website:

<a href="itms-services://?action=download-manifest&url=https://my-app.vercel.app/1.0.0/manifest.plist">Install App</a>

I want this app to be downloadable by everyone like apps like PandaHelper, AppValley, etc. I delivered my App's archive with AdHoc. The problem is that when I click on the link, I get asked if I want to download my App, but when I click yes I can't open my App after the download is finished. I just got an error that my App couldn't be verified.