Can't format message 13:98 ... firebird.msg not found

This error message has nothing to do with IBExpert itself, but with the client configuration.

Change the default value in the IBExpert database registration to the file fbclient.dll in the Firebird 3 subdirectory, then this message should no longer be displayed, as a suitable firebird.msg is also located there (see here under item 15 https://www.ibexpert.net/ibe/index.php?n=Doc.RegisterDatabase#ClientLib.

However, the second message is based on the user name/password combination, which does not correspond to the setting in your database server. One question: Which Firebird server version are you using?

If you require further assistance, we can support you with our IBExpert & Firebird Hotline