Most people in the thread so far seem to be thinking you are looking for a way to organise your photos from around the company. If this is what you want then dropbox and google drive are pretty good.
If you are looking for a publishing platform like Buffer (which does an awesome job of scheduling posts to twitter, FB and Linkedin for example) Instagram restricts the ability to post from publishing platforms, and their API documentation is very clear restricting any activity (including third party publishing) that may reduce the quality of posts on the platform. It is a premium environment so you can see why they don't want spam. It is worth reading this blog post
if only to moderate your own publishing guidelines.
So, as they grow more commercial there are signs that they are allowing a bit more leeway in this area, but partner schedulers are being held to account so be careful about paying a lump sum to services that may be cut off in a few months. As mentioned by Stan, Instagram's public stance is not to allow third party publishing apps.
Schedugram seems to have a good offering (not used it) but it is a paid for service http://schedugr.am
that allows you to schedule posts from your desktop machine.
If you are not scheduling too many posts and you don't use Instagram personally on your own phone, then I would manage using a combination of Dropbox/Google Drive. Use their mobile app to drop the images on your phone and then use your the instagram app on the phone to publish.