It is possible to connect your basic Instagram account with email and password, but your basic Instagram account only enables you to collect public Instagram posts by your own account.
If you want to collect public posts from any Instagram Business Account or all public images/videos mentioning a hashtag, we will ask you to connect your Instagram Business account which is connected to your Facebook Page via your Facebook account.
Instagram doesn't have user management for a company account (also known as Business Account). Therefore, Instagram uses a Facebook connection to check if you administrate at least one Facebook Page and if there's an Instagram Business Account connected to it. That is a requirement by Facebook and Instagram to all third-party applications and part of their terms and conditions for developers.
Before getting started with Instagram Feed, please check:
Are you an admin of at least one Facebook Page? You can confirm that by navigating to your company's Page on Facebook and checking your Page Role from Page Settings.
Does that Facebook Page have an Instagram Business Account connected? You can check this by logging in to the Instagram app and clicking 'Edit Settings'. From settings, you should find the connected Facebook Page. If the Page is not visible, make sure your Instagram account is a Business Account and then connect the Page.
Here you will find more information on how to switch your Instagram Account to a Business version and to link it to a Facebook Page.