If there are multiple servers are being used for the setup and installation of the iVend then make sure that there is no connection issue between App server (where installing the iVend) and Database server.
It is observed in such cases that network issue causes this error when Database server and App server are having connection issue and not able to connect with each other properly.
One of the way to check the Connection between servers is by using data link (UDL) file, below is the KB link for the same:
https://help.ivend.com/portal/en/kb/articles/how-to-check-the-connectivity-is-in-place-between-the-ivend-component-and-the-corresponding-database-1-12-2023Below is another link to explore it further:
If you find any connection issue between the servers then resolve the connection issue which should resolve the reported error "Please provide valid SQL Credentials" as well.
This KB article concludes here.