Go to your Instagram account and sign in.
Click on your profile page.
Once on your profile page right click anywhere on a blank spot.
Click on the dropdown menu and choose "inspect."
At the top of the inspect menu there will be a toggle device toolbar.
Click on the toggle icon to change the view.
At the top of the box there is a dropdown menu that says "responsive." Click on the arrow to bring down a list and choose another device type.
Click the x to exit the "inspect" menu.
You may have to refresh the Instagram page to be able to see the tool bar at the bottom of the page.
You can now click on the + (plus sign) to add things to your Instagram page.
I don't know if this works on all laptop or desktop browser boxes or not, but I am using Microsoft Edge on this one and this was how it worked. Please let me know if this worked on other browser boxes or not. Thank you.
Here is another blog with other directions if you would like to check it out. https://vivaldi.com/blog/instagram-post-from-computer/