What can I do about a hanging MyCollab installation on Linux?

MyCollab displays an initial setup screen a la Wordpress, but the installer hangs, regardless of how permissive I've set its directory to be.

When I test a database connection, it said that it can't make a connection. I have specified the database name, a user with access to that database, the corresponding password, and the address. If I click "Check connection" it says "Cannot connect to database. Recheck your input."

I am not sure what it's not connecting to. I can use a mysql -ufoo -p, giving the same credentials as I gave MyCollab, and telnetting to localhost on 3306 gets binary data that includes an intelligible MariaDB prompt. I can use the database from the command line.

What else should I be doing?