Update Kernel HP ProBook 450 G8 Notebook PC (16 GB) (202106-29176)

My Laptop is not recognizing external monitors and the touchpad is not working neither. The Laptop system seems to be certified with Ubuntu tested with 20.04 LTS, running the 5.10.0-1038-oem kernel.

My kernel version is the 5.04 and it seems that there are updates on the software updater. I've tried to update it manually to the 5.10 and 5.13 versions following this tutorial (https://itsfoss.com/upgrade-linux-kernel-ubuntu/) but when the Laptop tries to boot it says that it can load the kernel since it has an invalid signature.

How can I fix my problem and start using external monitors and the touchpad us well?

Thank you