After you have installed the RouterOS software, or turned on the Router for the first time, there are various ways how to connect to it:

Accessing Command Line Interface (CLI) via Telnet, SSH, serial cable or even keyboard and monitor if your router has a VGA card.
Accessing Web based GUI (WebFig)
Using the WinBox configuration utility (Windows app, compatible with Wine)
Every router is factory pre-configured with the IP address 192.168.88.1/24 on the ether1 port. The default username is admin with no password. After you log in for the first time, please create a new user with a password in the "full" group, re-login and delete the default admin user. We highly recommend you to follow the general guidelines of the article Securing your router to protect the device from any unauthorised access.