Can't get in macOS Utilities
Since Mojave isn't officially supported the recovery partition might be missing.
An alternate way to access the utilities without the CMD+R is to create an install usb. To do this first pick which version you want.

Download image. Downloads can be found at this apple page
Find a 16GB usb flash drive to put the image on (back up all data from it because it will be erased).
Create the usb. You can find the right commands here.
Boot off of the usb by holding down option when pressing the power button.
Access any utilities needed.