Check your lease - most of the time it says apartment must be returned to original condition (or something like that) so as long as you patch it over properly, you are in the clear. If it’s considered an upgrade, you can leave it in place when you move out without issue.

As people mentioned tension rods are great, as well as command hooks.

And there’s also privacy film you can buy to place on the window that typically peels off leaving no damage. (Read amazon reviews to find the best one)

/edit - typos