Getting this install error using latest CivicCRM on wordpress
It seems like you have two problems.

As Pradeep mentioned in the comments - it seems like your underlying error is that the install is trying to create a database that already exists.  I can't tell for sure, because the error in #4 is cut off.

Additionally, there's the second error (undefined function) which is unfortunately WordPress-specific and I don't know the solution.  However, completely removing/creating the CiviCRM database again (assuming that it's separate from WordPress) is likely to solve the first problem, and the second problem won't occur.