Hello ppam,
Thanks for posting in the Apple Support Communities.
If you're seeing this occur with your MacBook Air as opposed to other Apple devices, see if quitting the Safari browser will allow the login information to appear as this is considered a captive network. In addition, you may need credentials from the hotel staff, so be sure you have the information needed from them. For assistance with closing an app completely, check out the steps below or here: Quit apps on Mac - Apple Support
• To quit an app, choose App Name > Quit App in the menu bar. For example, choose Preview > Quit Preview (or press the keyboard shortcut Command-Q).
Keep in mind that if you click the Close button in the top-left corner of an app’s window, the window closes, but the app remains open (a small dot below the app’s icon in the Dock indicates that the app’s open).
If that's not helpful, confirm the current installed macOS version as well as more details on what occurs when you try to open a website with a captive network.
Have a great day!