I don't have access to all of my Instagram accounts
When you click the icon in the app, and then click the Manage Accounts button, is the account you want to add to oneclick.bio not displayed in the popup? If it isn't, there's one of two potential problems.
1. We have an old access token for you. To remedy this, click the Disconnect Facebook Account button under the same menu. Next, go to https://www.facebook.com/settings?tab=business_tools&ref=settings, and remove the oneclick.bio app. After you've done that, go back to oneclick.bio, and re-authenticate with Facebook. (you will be prompted to do so) Make sure you've selected all of the Instagram accounts you want to use when re-authenticating with Facebook.
2. You don't have Admin access to the Instagram account. If after doing #1, all of your accounts still aren't there, you do not have Administrator access to the account on Facebook. To fix this, you can either have the owner of the account give you access to it. (and then repeat the steps in #1) Or, have the owner of the account add oneclick.bio, and then have them share it with you by clicking the icon in the app. (the owner of the account should be a Hootsuite team administrator for this to work, which they usually are)
Please note that while you may have access to all of the Instagram accounts within Hootsuite itself, that isn't enough. oneclick.bio itself needs access to the Instagram account, and that can be achieved by either having access given to you on Facebook, or, by having the owner of the account give you access to it inside oneclick.bio.