If you would like to upload photos to Instagram from a desktop/laptop computer, here's a neat trick.
First, you will have to turn on Develop Mode in your web browser. Each web browser has this in a different location. In the video I use Safari but this should work in your browser as well.
For Safari: Go to Safari > Preferences > Advanced. Check the box at the very bottom that says, "Show Develop menu in menu bar."
Now open a private browsing window. Head to Develop > User Agent > Safari -- iOS 10 -- iPhone. Go to Instagram.com, sign in and click the camera button at the bottom of the screen to upload a photo from your desktop.
In Chrome, go to Instagram.com and sign in. Now right-click the page > Inspect > click the Tablet icon (top-left). The page should switch to mobile view, where you'll find a camera button at the bottom of the screen, which lets you upload a photo from your desktop.
If you have any questions, comments or would like to add to this post ( How to turn on develop mode in other browsers) let me know in the comments below.