You can overcome the problem by looking in your device map (first must be
disk not, usb stick) - it is under bootloader installation details.
The device map you can find in yast2 bootloader -> bootloader installation
details during the installation process. As described in the bug report you
get after the initial error a possibility to correct the boot parameters
and look then what the device map says and correct as needed
If the stick boots Ubuntu, probably it will work to boot the openSUSE installer as well. I would encourage you to look at not only the howto’s but the several lengthy threads on this forum which deal with using such a device once installed. There are often issues with what the bios supports, how a bios boot setup will work between USB and internals drives, etc. You may save yourself a lot of time and possibly frusration taking a long at that information in advance.