After a fresh installation of Excel, I can no longer get the connection to Exactonline NL working.\I enter the details from the Exact App Center, but I get an error message.
For Invantive Control for Excel and other on-premises products, a redirect URL can be used such as https://clientredirect.invantive.com or a custom redirect URL via HTTPS.
The error message indicates that the OAuth redirect URI must be the same as in the settings in Exact Online. Do the values being used match? Also see the related forum topics at the bottom of the error message.
I first tried it with the link provided in the app settings of Exact for this application. It then indicates that the link is not suitable for this version.