Dual Boot Ubuntu on SSD on Macbook Pro 2013 Please Help

Hi,

As the title says, I am trying to dual boot, I followed the guide here: https://florisvanbreugel.wordpress.com/2018/03/23/installing-ubuntu-on-an-external-ssd-drive-on-a-macbook/.

I am getting the following error:

Failed to Set MokListRT: Invalid Parameter
Could not create mokListRT: Invalid Parameter
Importing MOK states has failed: import_mok_state() failed: Invalid Parameter
Continuing boot since secure mode is disabled.

I tried the following here: https://askubuntu.com/questions/1279602/ubuntu-20-04-failed-to-set-moklistrt-invallid-parameter.

I do not know where I can run this,l I also tried reFINd:

sudo su -
cd /boot/efi/EFI/ubuntu
cp grubx64.efi shimx64.efi
reboot

This looks like a technical support (help) request.

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