Need help with Facebook and LinkedIn App Review process

Hi, I'm looking for help with the review process for an app for both LinkedIn and Facebook pages (includes Instagram).

We are developing a web app from which our clients would be able to directly publish content to their Instagram, facebook page and Linkedin Page, but we're unsure of the requirements for approval from either sites. We need assistance ensuring that my app meets the technical requirements for both social media sites and getting an approved review.

Take into consideration that the Apps approval process might take some time to complete while both companies make the verifications and we will need you for the whole process, so the job ends when the apps get approved

If you have experience with the review process for either or both of these sites, then I look forward to hearing from you. Thank you for your help.