Please follow these steps in order to connect your Instagram Account:
1) You need to set your Instagram language to English in the app first from which you can see more info here: https://help.instagram.com/111923612310997
2) Then you need to set English as your main language for the Chrome browser (or any default browser you use). You need to paste this in your browser: chrome://settings/?search . Then write "Language" in your browser's main language to the search bar. Here you should set English to be the first language.
3) Then log out of your Instagram account and log into it again.
4) Finally try to connect your Instagram account to your Post For Rent profile again and it should work.