While scheduling and posting works the same way for other social accounts, posting to Instagram works a little differently on third-party apps like Crowdfire.
When you schedule a post, Crowdfire reminds you about it with a notification on your phone, opens the Instagram app and copies your caption to the clipboard. All you have to do is paste the caption and post!
Also, to post to Instagram - you need to have the latest versions of Crowdfire and Instagram apps installed on your mobile.
Note: Instagram allows you to use up to 30 hashtags in one post and that there is an overall character limit of 2200 characters. Exceeding any of these limits can be a reason why your content fails to be uploaded.