Yes, you can use MSAL on a non-SPA website. MSAL supports both SPA and non-SPA web applications.
It sounds like the issue you're experiencing with the endless loop may be due to incorrect configuration or usage of MSAL. It's important to ensure that your redirect URI is correctly configured in your MSAL application registration in Azure Active Directory. Additionally, you should check that the scopes you are requesting are appropriate for your application.
To help with troubleshooting, you can enable verbose logging in MSAL. This will provide additional details about the authentication flow and may help you identify the root cause of the issue.
Overall, it's recommended to migrate from ADAL to MSAL as ADAL is being deprecated. However, if you're unable to get MSAL working in a reasonable amount of time, it may be worth considering continuing to use ADAL until you're able to build a new version of the site as a SPA.