Unable to download IPA on iPhone

At my work we have 3 systems, that is dev, qa & prod. We are unable to download our custom Neptune apps for dev & qa system. Prod is working perfect. On our Neptune app store we are not get the download pop-up button when clicking install in dev & qa. However, prod is working perfect, we have done most things even consulted the Neptune company. Is there developers we can contact from apple to help us with this very urgent issue?

Unable to download IPA on iPhone
 
 
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