We need to know a few details about your Developer accounts to get them linked - here's what we're looking for and where to find it.
Google Play Developer Account
Google Play Account Name - You'll find this in your Google Play developer account under Settings > Account Details
Google Play Account Number - You'll find this number in the URL for your Google Play developer account. EG. https://play.google.com/apps/publish/?account=1234567890123456789#AppListPlace
Google Email Address - You'll find this email address under the Users & Permissions section of the Settings on your Google Play developer account.
This is also the same email address you used when you set up the account.
Google Play Registration ID - This is the Registration ID from your receipt for the Google Play Developer Account registration fee (you'll find your account registration ID on the receipt that was emailed to you when you registered for your account.) Tip: If you can't find it in your email, check your transactions on the account you used to pay the account registration fee. Transactions IDs for registrations are typically in one of the following formats:
Apple Developer Account
Apple Developer Account Name - You'll find the name of your Developer account on the Membership tab of your Apple Developer account. It is referred to here as the Team Name
Apple Developer Account Agent ID - This is the email address associated with your Apple Developer account Agent's Apple ID. The email address you use when you login to the developer account. If you're not sure which email address this is, you'll see it in the App Store Connect account under Users and Access
Apple Developer Team ID - You'll find this ID number on the Membership tab of your Apple Developer account.